View:
Download DOC
Download PDF
Download XLS
Prepared by MERRILL CORPORATION www.edgaradvantage.com QuickLinks -- Click here to rapidly navigate through this document

As filed with the Securities and Exchange Commission on August 11, 2000

Registration No. 333-    

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-4

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

YAHOO! INC.

(Exact Name of Registrant as Specified in its Charter)

Delaware
(State or other jurisdiction of
incorporation or organization)		   7373
(Primary Standard Industrial
Classification Code Number)		   77-0398689
(I.R.S. Employer
Identification Number)

3420 Central Expressway
Santa Clara, California 95051
(408) 731-3300
(Address, Including Zip Code, and Telephone Number, Including Area Code, of
Registrant's Principal Executive Offices)

Susan Decker
Senior Vice President, Finance and Administration, and Chief Financial Officer
Yahoo! Inc.
3420 Central Expressway
Santa Clara, California 95051
(408) 731-3300
(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service)

With Copies to:

Joshua L. Green
Steven J. Tonsfeldt
Mark W. Seneca
Venture Law Group
A Professional Corporation
2800 Sand Hill Road
Menlo Park, California 94025
(650) 854-4488

   Approximate date of commencement of proposed sale to the public: from time to time after this registration statement becomes effective.

   If the securities being registered on this form are being offered in connection with the formation of a holding company and there is compliance with general Instruction G, check the following box / /.

   If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act of 1933, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering / /         .

   If this form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering / /         .

   If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act, check the following box /x/.

CALCULATION OF REGISTRATION FEE

Title of each class of
securities to be registered
   Amount to be
registered (1)
   Proposed maximum
offering price
per share (2)
   Proposed maximum
Aggregate
Offering Price (2)
   Amount of
registration fee (3)
Common Stock, par value $0.001 per share   7,500,000   $130.6625   $979,968,750   $258,711.75
(1)
The shares of common stock set forth in the Calculation of Registration Fee Table, and which may be offered pursuant to this Registration Statement, includes, pursuant to Rule 416 of the Securities Act of 1933, as amended (the "Securities Act"), such additional number of shares of the Registrant's common stock that may become issuable as a result of any stock splits, stock dividends or similar event.
(2)
Estimated solely for the purpose of calculating the registration fee, based on the average of the high and low prices for the Company's common stock as reported on the Nasdaq National Market on August 10, 2000 in accordance with Rule 457(c) under the Securities Act.
(3)
Pursuant to Rule 429 under the Securities Act, 2,417,734 shares and the filing fee of $123,028.81 paid with respect to those shares are being carried forward from Registration Statement No. 333-94537 to this Registration Statement. Therefore, a registration fee of $135,682.94 is being paid in connection with the filing of this Registration Statement.

   The Registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

Subject to Completion dated August 11, 2000

Prospectus

Yahoo! Inc.
7,500,000 Shares of Common Stock

    This prospectus relates to 7,500,000 shares of common stock that may be offered and issued from time to time in connection with acquisitions of other businesses, assets or securities.

    The amount and type of consideration we will offer and the other specific terms of each acquisition will be determined by negotiations with the owners or controlling persons of the businesses, assets or securities to be acquired. We may structure business acquisitions in a variety of ways, including acquiring stock, other equity interests or assets of the acquired business or merging the acquired business with us or one of our subsidiaries. We do not expect to receive any cash proceeds from the sale of shares of common stock issued pursuant to this prospectus. We may be required to provide further information by means of a post-effective amendment to the registration statement or a supplement to this prospectus once we know the actual information concerning a specific acquisition.

    We will pay all expenses of this offering. We will not pay underwriting discounts or commissions in connection with issuing these shares, although we may pay finder's fees in specific acquisitions. Any person receiving a finder's fee may be deemed an underwriter within the meaning of the Securities Act of 1933.

    We may also permit individuals or entities who have received or will receive shares of our common stock in connection with the acquisitions described above to use this prospectus to cover resales of those shares. See "Selling Stockholders" for the identity of any such individuals or entities.

    Our common stock is quoted on the Nasdaq National Market under the symbol "YHOO." On August 10, 2000, the reported last sale price for the common stock on Nasdaq was $129.3125 per share.

    INVESTING IN OUR COMMON STOCK INVOLVES A HIGH DEGREE OF RISK. YOU SHOULD CAREFULLY CONSIDER THE "RISK FACTORS" BEGINNING ON PAGE 3 IN DETERMINING WHETHER TO PURCHASE SHARES OF OUR COMMON STOCK.

    NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE ADEQUACY OR ACCURACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

    THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER TO SELL THESE SECURITIES AND IT IS NOT SOLICITING AN OFFER TO BUY THESE SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

The date of this prospectus is            , 2000


TABLE OF CONTENTS

 
   Page
Yahoo!   3
Risk Factors   3
Distribution of Securities   16
Selling Stockholders   16
Legal Matters   17
Experts   17
Where You Can Find More Information   17
Forward-Looking Statements   18

2

    THIS PROSPECTUS INCORPORATES IMPORTANT BUSINESS AND FINANCIAL INFORMATION THAT IS NOT INCLUDED IN OR DELIVERED WITH THIS PROSPECTUS. THIS INFORMATION IS AVAILABLE WITHOUT CHARGE TO SECURITY HOLDERS UPON ORAL OR WRITTEN REQUEST TO YAHOO! INC., ATTN: ANDREA KLIPFEL, INVESTOR RELATIONS, 3420 CENTRAL EXPRESSWAY, SANTA CLARA, CALIFORNIA 95051, TEL: (408) 731-3300. TO ENSURE TIMELY DELIVERY OF THE REQUESTED INFORMATION, YOU SHOULD MAKE YOUR REQUEST AT LEAST FIVE BUSINESS DAYS BEFORE THE DATE UPON WHICH YOU MUST MAKE YOUR INVESTMENT DECISION.

    WE HAVE NOT AUTHORIZED ANY PERSON TO PROVIDE INFORMATION OR MAKE ANY REPRESENTATION ABOUT THIS OFFERING THAT IS NOT IN THIS PROSPECTUS. PROSPECTIVE INVESTORS SHOULD RELY ONLY ON THE INFORMATION CONTAINED IN THIS PROSPECTUS. THIS PROSPECTUS IS NOT AN OFFER TO SELL NOR IS IT SEEKING AN OFFER TO BUY THESE SECURITIES IN ANY JURISDICTION WHERE THE OFFER OR SALE IS PROHIBITED. INFORMATION IN THIS PROSPECTUS IS CORRECT ONLY AS OF ITS DATE, REGARDLESS OF WHEN ANY LATER OFFER OR SALE OCCURS.


YAHOO!

About Yahoo!

    Yahoo! is a global Internet communications, commerce and media company that offers a comprehensive branded network of services to more than 156 million individuals each month worldwide. As the first online navigational guide to the Web, www.yahoo.com is the leading guide in terms of traffic, advertising, household and business user reach, and is one of the most recognized brands associated with the Internet. Yahoo! also provides online business services designed to enhance Yahoo!'s clients, including audio and video streaming, store hosting and management, and Web site tools and services. Yahoo!'s global Web network includes 23 local world properties outside the United States. Yahoo! has offices in Europe, Asia Pacific, Latin America, Canada and the United States, and is headquartered in Santa Clara, California.

    Yahoo! was incorporated on March 5, 1995 under the laws of California. Yahoo! was subsequently reincorporated on May 18, 1999 under the laws of Delaware. Our principal executive offices are located at 3420 Central Expressway, Santa Clara, California 95051 and our telephone number is (408) 731-3300. As used in this prospectus, the "we," "us," "our" and "Yahoo!" refer to Yahoo! Inc., a Delaware corporation, and its wholly-owned subsidiaries, including GeoCities and broadcast.com.


RISK FACTORS

We are in a highly competitive industry and some of our competitors may be more successful in attracting and retaining customers.

    The market for Internet products and services is highly competitive and we expect that competition will continue to intensify. Negative competitive developments could have a material adverse effect on our business and the trading price of our stock.

    We compete with many other providers of online navigation, information, entertainment, business, community, electronic commerce and broadcast services. As we expand the scope of our Internet offerings, we will compete directly with a greater number of Internet sites, media companies, and companies providing business services across a wide range of different online services, including:

3

    In particular, we face significant competition from America Online and Microsoft (MSN) and, to a less significant extent, other companies that have combined a variety of services under one brand in a manner similar to Yahoo! including CMGI (Alta Vista), the Walt Disney Company (The GO Network), Excite@Home, and Lycos. In certain of these cases, our competition has a direct billing relationship with the user, which we generally lack. This relationship permits our competitors to have several potential advantages including the potential to be more effective than us in targeting services and advertisements to the specific taste of their users. America Online and Time Warner recently approved the proposed merging of their companies and this transaction is now expected to close, subject to receipt of regulatory approval. If completed, the merger will provide America Online with content from Time Warner's movie and television, music, books and periodicals, news, sports and other media holdings; access to a network of cable and other broadband delivery technologies; and considerable resources for future growth and expansion. The proposed America Online and Time Warner combination will also provide America Online with access to a broad potential customer base consisting of Time Warner's current customers and subscribers of its various media properties. We also face competition from Web sites focused on vertical markets where expertise in a particular segment of the market may provide a competitive advantage. On an international level, we compete directly with local providers; they may have several advantages, including greater knowledge about the particular country or local market and access to significant financial or strategic resources in such local markets. We must continue to obtain more knowledge about our users and their preferences as well as increase our branding and other marketing activities in order to remain competitive.

    A large number of these Web sites and online services as well as high-traffic e-commerce merchants such as Amazon.com, Inc. also offer or are expected to offer informational and community features that may be competitive with the services that we offer. In order to effectively compete, we may need to expend significant internal engineering resources or acquire other technologies and companies to provide or enhance such capabilities. Any of these efforts could have a material adverse effect on our business, operating results and financial condition and be dilutive to our stockholders.

Financial results for any particular period will not predict results for future periods.

    Because of the uncertain nature of the rapidly changing market we serve, period-to-period comparisons of operating results are not likely to be meaningful. In addition, you should not rely on the results for any period as an indication of future performance. In particular, although we experienced strong revenue growth through the first half of 2000, we do not believe that this level of revenue growth on a percentage basis will be sustained in future periods, particularly on a long-term basis. In addition, we currently expect that our operating expenses will continue to increase significantly as we expand our sales and marketing operations, continue to develop and extend the Yahoo! brand, fund greater levels of product development, develop and commercialize additional media properties, and acquire complementary businesses and technologies. Further, we are subject to employer payroll taxes when our employees exercise their non-qualified stock options. The employer payroll taxes are assessed on each employee's gain, which is the difference between the price of our common stock on the date of exercise and the exercise price. During a particular period, these payroll taxes could be material. Assuming the fair market value of our common stock was $125 per share on June 30, 2000, employer payroll taxes on unrealized gains related to vested and unvested non-qualified stock options would be approximately $48.1 million and $73.2 million, respectively. These employer payroll taxes would be recorded as a charge to operations in the period such options are exercised based on actual gains realized by employees. Net proceeds that we would receive upon the exercise of such vested and unvested stock options would approximate $360.7 million and

4

$2.2 billion, respectively. In addition, we would receive tax deductions for gains realized by employees on the exercise of non-qualified stock options for which the benefit is recorded as additional paid-in capital. However, because we are unable to predict our future stock price and the number of optionees who may exercise during any particular period, we cannot predict what, if any, expense will be recorded in a future period and the impact on our future financial results. In addition, if revenue growth levels do not meet our expectations, our financial results will be adversely affected.

We rely heavily on revenues derived from Internet advertising, which may prove to be an ineffective means of advertising for our current and potential clients.

    Currently, the majority of our revenues come from advertisements displayed on our online properties. Our ability to continue to achieve substantial advertising revenue depends upon:

    In addition, we have recently experienced a shift in the source of advertising revenues from Internet companies to companies in more traditional lines of business. These advertisers often have substantially different requirements and expectations than Internet companies with respect to advertising programs. If we are unsuccessful in adapting to the needs of our advertisers, it could have a material adverse effect on our business, operating results and financial condition.

We derive the majority of our revenues from the sale of advertisements under short-term contracts, which are difficult to forecast accurately.

    Most of our revenues are currently derived from agreements with advertisers or sponsorship arrangements. These agreements generally have terms no longer than three (3) years and, in many cases, the terms are much shorter. In cases where the advertiser is providing services, the agreements often have payments contingent on usage levels. Many of our advertisers are Internet companies which, in certain cases, may lack financial resources to fulfill their commitments. Accordingly, it is difficult to accurately forecast these revenues. However, our expense levels are based in part on expectations of future revenues and are fixed over the short term with respect to certain categories. We may be unable to adjust spending quickly enough to compensate for any unexpected revenue shortfall. Accordingly, the cancellation or deferral of advertising or sponsorship contracts could have a material adverse effect on our financial results. Because our operating expenses are likely to increase significantly over the near term, to the extent that our expenses increase but our revenues do not, our business, operating results, and financial condition may be materially and adversely affected.

The rate structure of some of our sponsorship arrangements subjects us to financial risk.

    A key element of our strategy is to generate advertising revenues through sponsored services and placements by third parties in our online media properties in addition to banner advertising. We typically receive sponsorship fees or a portion of transaction revenues in return for minimum levels of user impressions to be provided by us. These arrangements expose us to potentially significant financial risks in the event our usage levels decrease, including the following:

5

    Accordingly, any leveling off or decrease of our user base or the failure to generate anticipated levels of shared transaction revenues could result in a significant decrease in our revenue levels.

We have spent considerable amounts of money and resources to provide a variety of communications services, but such services may not prove to be successful.

    Currently, a substantial portion of the traffic on our online properties is directed at our communications services, such as email, instant messaging, calendaring and chat rooms, and we expect this trend to continue for the foreseeable future. We provide these and other basic communications services free of charge to our users, as is the case with most of our competitors, and have not yet determined an effective means of generating revenues directly from the provision of such services. Alternative revenue models for our communications and electronic commerce services, such as subscription fees and commissions, are relatively unproven and may not generate sufficient revenues to be meaningful to us. Currently, we are dependent upon the use of other Yahoo! services to generate revenues from our communication services, and there is a risk that this relationship will not be sustained. As communications services become an increasingly important part of our total offering, we must continue to provide new communications applications which are compelling to users and utilize more sophisticated communications technologies to provide such applications to many types of access devices in addition to the personal computer, while continuing to develop an effective method for generating revenues for such services. In addition, the development of these technologies require long development cycles and a more significant investment by us. If we were unable to develop such applications or use such technologies, the size and rate of growth in our user base would be adversely affected. If we cannot develop a direct or indirect means by which we generate revenues from our communications services that are more than sufficient to offset the costs of providing such services, our business, operating results and financial condition would be materially adversely affected.

We may not be successful in expanding the number of users of our electronic commerce services and our ability to effectively provide these services is limited because we do not have a direct billing relationship with our customers.

    We have focused, and intend to continue to focus, significant resources on the development and enhancement of our electronic commerce properties. These properties, such as Yahoo! Shopping, link users with a network of retailers with which we have relationships. However, we merely provide a means through which our users can access the sellers of the products such users may wish to purchase and do not establish a direct billing relationship with our users as a result of any such purchase. In addition, a large number of our users currently utilize our online shopping services simply to gather information for future offline purchases. We will need to effectively induce information gatherers to make purchases in order for our electronic commerce properties to be successful. Finally, the success of our electronic commerce properties will also depend on, among other things, our ability to attract and retain well-known brands among our network of retailers. The revenue that we derive from our electronic commerce services is typically in the form of a bounty or a commission paid by the retailer from whom our user purchased a product. If the user had a favorable buying experience with a particular retailer, the user may subsequently contact that retailer directly rather than through our service. If our users bypass our electronic commerce properties, such as Yahoo! Shopping, and contact retailers directly, we will not receive any revenue for purchases made through such direct contact. Competing providers of online shopping, including merchants with which we have relationships, may be able to provide a more convenient and comprehensive online shopping experience due to their singular focus on electronic commerce. As a result, we may have difficulty competing with those merchants for users of electronic commerce services. The inability of our electronic commerce properties to generate significant revenues could have a material adverse effect on our business.

6

We will continue to expand into international markets in which we have limited experience.

    A key part of our strategy is to develop Yahoo!-branded online properties in international markets and we have developed, through joint ventures, subsidiaries and branch offices, Yahoo! properties localized for over 20 other countries. To date, we have only limited experience in developing localized versions of our products and marketing and operating our products and services internationally and we rely on the efforts and abilities of our foreign business partners in such activities.

    We believe that in light of substantial anticipated competition, we need to move quickly into international markets in order to effectively obtain market share. However, in a number of international markets, especially those in Europe, we face substantial competition from Internet Service Providers (ISPs) that offer or may offer their own navigational services. Many of these ISPs have a dominant market share in their territories. Further, foreign providers of competing online services may have a substantial advantage over us in attracting users in their country due to more established branding in that country, greater knowledge with respect to the tastes and preferences of users residing in that country and/or their focus on a single market. We have experienced and expect to continue to experience higher costs as a percentage of revenues in connection with the development and maintenance of international online properties. International markets we have selected may not develop at a rate that supports our level of investment. In particular, international markets typically are slower than domestic markets in adopting the Internet as an advertising and commerce medium.

    In addition to uncertainty about our ability to continue to generate revenues from our foreign operations and expand our international presence, there are certain risks inherent in doing business on an international level, including:

    One or more of these factors could have a material adverse effect on our future international operations and, consequently, on our business, operating results, and financial condition.

We depend on key personnel who may not continue to work for us.

    We are substantially dependent on the continued services of our key personnel, including our two founders, our chief executive officer, president, chief financial officer, chief technical officer and vice presidents. These individuals have acquired specialized knowledge and skills with respect to Yahoo! and its operations or, in the case of our chief financial officer, only recently joined us. If any of these individuals were to leave Yahoo!, we could face substantial difficulty in hiring qualified successors and could experience a loss in productivity while any such successor obtains the necessary training and experience. Many of our management personnel have reached or will soon reach the four-year anniversary of their Yahoo! hiring date and, as a result, will have become or will shortly become fully vested in their initial stock option grants. While management personnel are typically granted additional stock options, which will usually vest over a period of four years, subsequent to their hire date to provide additional incentive to

7

remain at Yahoo!, the initial option grant is typically the largest and an employee may be more likely to leave our employ upon completion of the vesting period for the initial option grant.

    We expect that we will need to hire additional personnel in all areas. The competition for qualified personnel is intense, particularly in the San Francisco Bay Area, where our corporate headquarters are located. At times, we have experienced difficulties in hiring personnel with the right training or experience, particularly in technical areas. We do not maintain key person life insurance for any of our personnel. If we do not succeed in attracting new personnel, or retaining and motivating existing personnel, our business will be adversely affected.

We may have difficulty scaling and adapting our existing architecture to accommodate increased traffic and technology advances.

    Yahoo! is one of the most highly trafficked Web sites on the Internet and is regularly exceeding previous standards for numbers of simultaneous users, unique users and daily page views delivered. In addition, the services offered by Yahoo! and popular with users have changed significantly in the past and are expected to change rapidly in the future. Much of the architecture that we employ was not originally designed to accommodate levels or types of use that we currently experience on our online properties and it is unclear whether current or future anticipated levels of traffic will result in delays or interruptions in our service. In particular, the architecture utilized for our email and certain other communication services was not primarily designed for this purpose, is highly complex and may not provide satisfactory service in the future, especially as it becomes an increasingly important service offering. In the future, we may be required to make significant changes to our architecture, including moving to a completely new architecture. If we are required to switch architectures, we may incur substantial costs and experience delays or interruptions in our service. If we experience delays or interruptions in our service due to inadequacies in our current architecture or as a result of a change in architectures, users may become dissatisfied with our service and move to competing providers of online services. Further, to the extent that demand for our broadcast services content increases, we will need to expand our infrastructure, including the capacity of our hardware servers and the sophistication of our software. This expansion is likely to be expensive and complex and require additional technical expertise. Also, as we acquire users who rely upon us for a wide variety of services, it becomes more technologically complex and costly to retrieve, store and integrate data that will enable us to track each user's preferences. Any loss of traffic, increased costs, inefficiencies or failures to adapt to new technologies and the associated adjustments to our architecture would have a material adverse effect on our business.

Our competitors often provide Internet access or computer hardware to our customers and they could make it difficult for our customers to access our services.

    Our users must access our services through an Internet service provider, or ISP, with which the user establishes a direct billing relationship using a personal computer or other access device. To the extent that an access provider, such as America Online, or a computer or computing device manufacturer offers online services or properties that are competitive with those of Yahoo!, the user may find it more convenient to use the services or properties of that access provider or manufacturer. In addition, the access provider or manufacturer may make it difficult to access our services by not listing them in the access provider's or manufacturer's own directory. Also, because an access provider gathers information from the user in connection with the establishment of the billing relationship, an access provider may be more effective than Yahoo! in tailoring services and advertisements to the specific tastes of the user. To the extent that a user opts to use the services offered by his or her access provider or those offered by computer or computing device manufacturers rather than the services provided by Yahoo!, our business, operating results and financial condition will be materially adversely affected.

8

Our business services, while costly to develop, may fail to gain market acceptance.

    We have invested a significant amount of money and resources in the creation of our business services, such as the creation and hosting of streaming content of third parties, but such services are unproven and may fail to gain market acceptance. Because the market for these business services is new and evolving, it is difficult to predict the size of this market and its rate of growth, if any. In addition, it is uncertain whether businesses and other organizations will utilize the Internet to any significant degree as a means of broadcasting business conferences and other events. Potential business services customers must accept audio and video broadcast services over the Internet as a viable alternative to face-to-face meetings, television or audio, audio teleconferences and video conferencing. We cannot assure you that the market for business services will continue to develop or be sustainable. If the market fails to develop, develops more slowly than expected or becomes more competitive than is currently expected, our operating results could be adversely affected.

More individuals are utilizing non-PC devices to access the Internet and we may not be successful in developing a version of our service that will gain widespread adoption by users of such devices.

    In the coming years, the number of individuals who access the Internet through devices other than a personal computer such as personal digital assistants, cellular telephones and television set-top devices is expected to increase dramatically. Our services are designed for rich, graphical environments such as those available on personal and laptop computers. The lower resolution, functionality and memory associated with alternative devices may make the use of our services through such devices difficult and we may be unsuccessful in our efforts to modify our online properties to provide a compelling service for users of alternative devices. As we have limited experience to date in operating versions of our service developed or optimized for users of alternative devices, it is difficult to predict the problems we may encounter in doing so and we may need to devote significant resources to the creation, support and maintenance of such versions. If we are unable to attract and retain a substantial number of alternative device users to our online services, we will fail to capture a sufficient share of an increasingly important portion of the market for online services. Further, as the majority of our revenues are derived through the sale of banner and other advertising optimized for a personal computer screen, we may not be successful at developing a viable strategy for deriving substantial revenues from online properties that are directed at the users of alternative devices. Any failure to develop revenue-generating online properties that are adopted by a significant number of handheld device users could have a material adverse effect on our business, operating results and financial condition.

We rely on the value of the Yahoo! brand and the costs of maintaining and enhancing our brand awareness are increasing.

    We believe that maintaining and expanding the Yahoo! brand is an important aspect of our efforts to attract and expand our user and advertiser base. We also believe that the importance of brand recognition will increase due to the growing number of Internet sites and the relatively low barriers to entry. We have spent considerable money and resources to date on the establishment and maintenance of the Yahoo! brand. However, because the number of Internet navigation, commerce, community and service companies continues to grow dramatically, it has become increasingly difficult and, due to increased competition, expensive, to obtain quality television, radio, magazine, Internet and other advertising space. Further, the proliferation of Internet-based companies has resulted and will continue to result in increased consumer confusion. Consequently, we will spend increasing amounts of money on, and devote greater resources to, advertising, marketing and other brand-building efforts to preserve and enhance consumer awareness of the Yahoo! brand during 2000. We may not be able to successfully maintain or enhance consumer awareness of our brand and, even if we are successful in our branding efforts, such efforts may not be cost-effective. If we are unable to maintain or enhance consumer awareness of the Yahoo! brand in a cost-effective manner, our business, operating results and financial condition would be materially and adversely affected.

9

The successful operation of our business depends upon the supply of critical elements from other companies.

    We will depend upon third parties, to a substantial extent, for several critical elements of our business including various technology, infrastructure, content development, software and distribution components.

    Technology and Infrastructure.  We rely on a private third-party provider, Frontier GlobalCenter, Inc., for our principal Internet connections. Email and other service Internet connections are provided to us by GTE. We rely on Network Appliances for key components of our email service. We also rely on Exodus Communications for the hosting of our users' homepages and Level 3 Communications for hosting and access to our broadcast services. Any disruption in the Internet access provided by these third-party providers or any failure of these third-party providers to handle current or higher volumes of use could have a material adverse effect on our business, operating results, and financial condition. We license technology and related databases from third parties for certain elements of our properties, including, among others, technology underlying the delivery of news, stock quotes and current financial information, chat services, street mapping and telephone listings, streaming capabilities and similar services. We have experienced and expect to continue to experience interruptions and delays in service and availability for such elements. Furthermore, we are dependent on hardware suppliers for prompt delivery, installation, and service of servers and other equipment to deliver our products and services. Any errors, failures, interruptions, or delays experienced in connection with these third-party technologies and information services could negatively impact our relationship with users and adversely affect our brand and our business, and could expose us to liabilities to third parties.

    Distribution Relationships.  To increase traffic for our online properties and make them more available and attractive to advertisers and consumers, we have certain distribution agreements and informal relationships with leading Web browser providers such as Microsoft, operators of online networks and leading Web sites, software developers and computer manufacturers, such as Toshiba, Hewlett-Packard and Gateway, and telecommunications companies, such as Sprint PCS. These distribution arrangements typically are not exclusive and do not extend over a significant amount of time. Further, some of our distributors are competitors or potential competitors who may not renew their distribution contracts with us. Potential distributors may not offer distribution of our properties and services on reasonable terms, or at all. In addition, as new methods for accessing the Web become available, we may be required to enter into additional distribution relationships. Any failure to obtain distribution or to obtain distribution on terms that are reasonable, could have a material adverse effect on our business, results of operations, and financial condition.

    Streaming Media Software.  We rely on the two leading providers of streaming media products, RealNetworks and Microsoft, to license the software necessary to broadcast streaming audio and video content to our users. There can be no assurance that these providers will continue to license these products to us on reasonable terms, or at all. Our users are currently able to electronically download copies of the software to play streaming media free of charge, but providers of streaming media products may begin charging users for copies of their player software or otherwise change their business model in a manner that slows the widespread acceptance of these products. In order for our broadcast services to be successful, there must be a large base of users of these streaming media products. We have limited or no control over the availability or acceptance of streaming media software, and to the extent that any of these circumstances occur, the broadcast services portion of our business will be materially adversely affected.

Our dependence on third-party content providers subjects us to risks.

    Our future success depends upon our ability to aggregate compelling content and deliver that content through our online properties. Much of the content that attracts users to the Yahoo! online properties, such as news items, stock quotes, weather reports, maps and audio and video content, is licensed from third parties such as Reuters and TIBCO. In particular, Yahoo! Broadcast relies on major sports organizations, radio and television stations, record labels, cable networks, businesses, colleges and universities, film

10

producers and distributors, and other organizations for a large portion of the content available on the site. Our ability to maintain and build relationships with third-party content providers will be critical to our success. We may be unable to enter into or preserve relationships with the third parties whose content we seek to obtain. Many of our current licenses for third-party content extend for a period of less than two years and there can be no guarantee that they will be renewed upon their expiration. In addition, as competition for compelling content increases both locally and abroad, Yahoo!'s content providers may increase the prices at which they offer their content to Yahoo! and potential content providers may not offer their content on terms agreeable to Yahoo!. An increase in the prices charged to us by third-party content providers could have a material adverse effect on our business, operating results and financial condition. Further, many of our content licenses with third parties are non-exclusive. Accordingly, other Webcasters may be able to offer similar or identical content. Likewise, most sports and entertainment content available on our online properties are also available on other media like radio or television. These media are currently, and for the foreseeable future will be, much more widely adopted for listening or viewing such content than the Web. These factors also increase the importance of our ability to deliver compelling editorial content and personalization of this content for users in order to differentiate ourselves. If we are unable to license or acquire compelling content, if other companies broadcast content that is similar to or the same as that provided by Yahoo!, or if we do not develop compelling editorial content or personalization services, the number of users on our online properties may not grow at all or at a slower rate than anticipated, which would decrease our advertising revenue.

As we provide more audio and video content, particularly music, we may be required to spend significant amounts of money on content acquisition and content broadcasts.

    Until recently, the majority of the content that we provided to our users was in print, picture or graphical format and was either created internally or licensed to us by third parties for little or no charge. However, we have been providing recently and we intend to continue to provide increasing amounts of audio and video content to our users, such as the broadcast of music, film content, speeches, news footage, concerts and other special events, through our broadcast services division and our other media properties, and such content may require us to make substantial payments to third parties from whom we will license or acquire such content. For example, in order to broadcast music through our online properties, we are currently required to pay royalties both on the copyright in the musical compositions and the copyright in the actual sound recordings of the music to be broadcast. Through our broadcast services division, we currently have license agreements in place with ASCAP and BMI, and are in negotiations for a license agreement with SESAC, that permit us to license the copyright for the public performance of musical compositions for which they control the rights. With respect to the copyrights in the specific sound recordings that we desire to broadcast, we must either secure a license directly from the record labels that own the rights to such recordings, or pay a statutory license fee. The statutory license fee and other terms for these licenses have not yet been determined and, therefore, the costs of broadcasting music through our online properties remains unclear. If these royalty rates are above our expectations, if the royalty rates charged by the various performance rights societies increase or if any of these or other parties with music licensing rights impose terms that make it difficult or impossible to broadcast music, we may be unable to provide music content to our users in a cost-effective manner. We believe that users of Internet services such as the Yahoo! online properties will increasingly demand high-quality audio and video content. The revenue that we receive as a result of our audio and video broadcasts may not justify the costs of providing such broadcasts. Our inability to cost-effectively provide high-quality audio and/or video content to our users could have a material adverse effect on our business, operating results and financial condition.

11

To successfully improve our rich media offerings, we must rely on the deployment of a true multicasting network.

    The streaming services that we acquired upon our acquisition of broadcast.com originally deployed unicasting (one user per company originated stream) technology to broadcast audio and video programming to users over the Internet. Recently, it began to deploy another broadcast technology, multicasting (multiple users per company originated stream). We believe that demand for multicasting will continue to expand and, as a result, we must continue to enhance this capability in the future.

    We will be required to test, deploy and successfully scale a multicast network infrastructure to serve mass audiences. There can be no assurance that we will be successful in doing so, that multicasting will be able to support a substantial audience or that an alternative technology will not emerge that offers superior broadcasting technology as compared to multicasting. In the event that multicasting technology is not successfully deployed in a timely manner or such an alternative technology emerges, we may be required to expend significant resources to deploy a technology other than multicasting, which could adversely affect our results of operations. If Yahoo! Broadcast Services fails to scale its broadcasts to large audiences of simultaneous users, such failure could adversely affect that portion of our business.

We must manage our growth successfully, including the integration of recently-acquired companies, in order to achieve our desired results.

    We have experienced dramatic growth in personnel in recent years and expect to continue to hire large numbers of additional personnel. As the number of Yahoo! employees grows, it will become increasingly difficult and more costly to manage our personnel. Further, as a result of recent acquisitions and international expansion, almost one-half of our employees are based outside of our Santa Clara headquarters. If we are unable to effectively manage a large and geographically dispersed group of employees, our business will be adversely affected.

    As part of our business strategy, we have completed several acquisitions and expect to enter into additional business combinations and acquisitions. Acquisition transactions are accompanied by a number of risks, including:

    We may not be successful in addressing these risks or any other problems encountered in connection with such acquisitions.

12

Our intellectual property rights are costly and difficult to protect.

    We regard our copyrights, trademarks, trade dress, trade secrets, and similar intellectual property, including our rights to certain domain names, as critical to our success. We rely upon trademark and copyright law, trade secret protection and confidentiality or license agreements with our employees, customers, partners and others to protect our proprietary rights. For example, we have obtained the registration for certain of our trademarks, including "Yahoo!" and "Yahooligans!" Effective trademark, copyright, and trade secret protection may not be available in every country in which our products and media properties are distributed or made available through the Internet, and while we attempt to ensure that the quality of our brand is maintained by our licensees, our licensees may take actions that could materially and adversely affect the value of our proprietary rights or the reputation of our products and media properties. We are aware that third parties have, from time to time, copied significant portions of Yahoo! directory listings for use in competitive Internet navigational tools and services. Protection of the distinctive elements of Yahoo! may not be available under copyright law. We cannot guarantee that the steps we have taken to protect our proprietary rights will be adequate.

We may be subject to intellectual property infringement claims, which are costly to defend and could limit our ability to use certain technologies in the future.

    Many parties are actively developing search, indexing, e-commerce and other Web-related technologies, as well as a variety of online business models and methods. We believe that these parties will continue to take steps to protect these technologies, including, but not limited to, seeking patent protection. As a result, disputes regarding the ownership of these technologies and rights associated with online business are likely to arise in the future. In addition to existing patents and intellectual property rights, we anticipate that additional third-party patents related to our services will be issued in the future. From time to time, parties assert patent infringement claims against us in the form of letters, lawsuits and other forms of communications. Currently, we are engaged in three lawsuits regarding patent issues and have been notified of a number of other potential disputes.

    In addition to patent claims, third parties have asserted and most likely will continue to assert claims against us alleging infringement of copyrights, trademark rights, trade secret rights or other proprietary rights, or alleging unfair competition or violations of privacy rights. In the event that we determine that licensing patents or other proprietary rights is appropriate, we cannot guarantee that we will be able to license such proprietary rights on reasonable terms or at all. We may incur substantial expenses in defending against third-party infringement claims regardless of the merit of such claims. In the event that there is a determination that we have infringed third-party proprietary rights or other third-party rights such as publicity and privacy rights, we could incur substantial monetary liability or be prevented from using the rights, which could require us to change our business practices in the future.

    We are aware of lawsuits filed against two of our competitors regarding the presentment of advertisements in response to search requests on "keywords" that may be trademarks of third parties. Initial rulings in these lawsuits were in favor of our competitors, but the plaintiffs in these lawsuits have appealed these initial rulings.

We are subject to U.S. and foreign government regulation of the Internet, the impact of which is difficult to predict.

    There are currently few laws or regulations directly applicable to the Internet. The application of existing laws and regulations to Yahoo! relating to issues such as user privacy, defamation, pricing, advertising, taxation, gambling, sweepstakes, promotions, content regulation, quality of products and services, and intellectual property ownership and infringement can be unclear. In addition, we will also be subject to new laws and regulations directly applicable to our activities. Any existing or new legislation

13

applicable to us could expose us to substantial liability, including significant expenses necessary to comply with such laws and regulations, and dampen the growth in use of the Web.

    Several recently passed federal laws could have an impact on our business. The Digital Millennium Copyright Act is intended to reduce the liability of online service providers for listing or linking to third-party Web sites that include materials that infringe copyrights or other rights of others. The Children's Online Protection Act and the Children's Online Privacy Protection Act are intended to restrict the distribution of certain materials deemed harmful to children and impose additional restrictions on the ability of online services to collect user information from minors. In addition, the Protection of Children From Sexual Predators Act of 1998 requires online service providers to report evidence of violations of federal child pornography laws under certain circumstances. Such legislation may impose significant additional costs on our business or subject us to additional liabilities.

    We post privacy policies concerning the use and disclosure of user data. In addition, GeoCities, a company we acquired in 1999, is required to comply with a consent order between it and the Federal Trade Commission (the "FTC"), which imposes certain obligations and restrictions with respect to information collected from users. Further, the FTC is conducting an inquiry into certain of our consumer information practices to determine whether we have complied with applicable FTC consumer protection regulations. In connection with this inquiry, the FTC has requested that we provide information about our practices and submit various documents and other materials to the FTC. Any failure by us to comply with our posted privacy policies, the consent order, FTC requirements (including the inquiry mentioned above) or other privacy-related laws and regulations could result in proceedings by the FTC or others which could potentially have an adverse effect on our business, results of operations and financial condition. In this regard, there are a large number of legislative proposals before the United States Congress and various state legislative bodies regarding privacy issues related to our business. It is not possible to predict whether or when such legislation may be adopted, and certain proposals, if adopted, could materially and adversely affect our business through a decrease in user registrations and revenues. This could be caused by, among other possible provisions, the required use of disclaimers or other requirements before users can utilize our services.

    Due to the global nature of the Web, it is possible that the governments of other states and foreign countries might attempt to regulate its transmissions or prosecute us for violations of their laws. We might unintentionally violate such laws, such laws may be modified and new laws may be enacted in the future. Any such developments could have a material adverse effect on our business, operating results and financial condition.

We may be subject to legal liability for our online services.

    We host a wide variety of services that enable individuals to exchange information, generate content, conduct business and engage in various online activities, including public message posting and services relating to online auctions and homesteading. The law relating to the liability of providers of these online services for activities of their users is currently unsettled. Claims have been threatened and could be brought against us for defamation, negligence, copyright or trademark infringement, unlawful activity, tort, including personal injury, fraud, or other theories based on the nature and content of information that we provide links to or that may be posted online or generated by our users or with respect to auctioned materials. In addition, we are aware that governmental agencies are currently investigating the conduct of online auctions.

    We also periodically enter into arrangements to offer third-party products, services, or content under the Yahoo! brand or via distribution on various Yahoo! properties, including stock quotes and trading information. We may be subject to claims concerning these products, services or content by virtue of our involvement in marketing, branding, broadcasting or providing access to them, even if we do not ourselves host, operate, provide, or provide access to these products, services or content. While our agreements with

14

these parties often provide that we will be indemnified against such liabilities, such indemnification may not be adequate.

    It is also possible that, if any information provided directly by us contains errors or is otherwise negligently provided to users, third parties could make claims against us. For example, we offer Web-based email services, which expose us to potential risks, such as liabilities or claims resulting from unsolicited email, lost or misdirected messages, illegal or fraudulent use of email, or interruptions or delays in email service. Investigating and defending any of these types of claims is expensive, even to the extent that the claims do not ultimately result in liability.

Our stock price has been volatile historically, which may make it more difficult for you to resell shares when you want at prices you find attractive.

    The trading price of our common stock has been and may continue to be subject to wide fluctuations. During the second quarter of 2000, the closing sale prices of our common stock on the Nasdaq Stock Market ranged from $112.0625 to $167.375 and the sale price of our common stock closed at $129.3125 on August 10, 2000. Our stock price may fluctuate in response to a number of events and factors, such as quarterly variations in operating results, announcements of technological innovations or new products and media properties by us or our competitors, changes in financial estimates and recommendations by securities analysts, the operating and stock price performance of other companies that investors may deem comparable, and news reports relating to trends in our markets. In addition, the stock market in general, and the market prices for Internet-related companies in particular, have experienced extreme volatility that often has been unrelated to the operating performance of such companies. These broad market and industry fluctuations may adversely affect the price of our stock, regardless of our operating performance.

Management and one large stockholder beneficially own approximately 39.4% of our stock; their interests could conflict with yours; significant sales of stock held by them could have a negative effect on Yahoo!'s stock price.

    Yahoo!'s directors and executive officers and SOFTBANK beneficially own approximately 39.4% of our outstanding common stock as of June 30, 2000. Eric Hippeau is a member of our Board of Directors and is also the Chairman and CEO of Ziff-Davis, a subsidiary of SOFTBANK. As a result of their ownership and positions, our directors and executive officers and SOFTBANK collectively are able to significantly influence all matters requiring stockholder approval, including the election of directors and approval of significant corporate transactions. Such concentration of ownership may also have the effect of delaying or preventing a change in control of Yahoo!. In addition, sales of significant amounts of shares held by Yahoo!'s directors and executive officers and SOFTBANK, or the prospect of these sales, could adversely affect the market price of Yahoo! common stock.

Our operations could be significantly hindered by the occurrence of a natural disaster or other catastrophic event.

    Our operations are susceptible to outages due to fire, floods, power loss, telecommunications failures, break-ins and similar events. In addition, the majority of our network infrastructure is located in Northern California, an area susceptible to earthquakes. We do not have multiple site capacity for all of our services in the event of any such occurrence. Despite our implementation of network security measures, our servers are vulnerable to computer viruses, break-ins, and similar disruptions from unauthorized tampering with our computer systems. In addition, we are vulnerable to coordinated attempts to overload our systems with data, resulting in denial or reduction of service to some or all of our users for a period of time. We have experienced a coordinated denial of service attack in the past, and may experience such attempts in the future. We do not carry sufficient business interruption insurance to compensate us for losses that may occur as a result of any of these events. Any such event could have a material adverse effect on our business, operating results, and financial condition.

15

Anti-takeover provisions could make it more difficult for a third party to acquire us.

    Our Board of Directors has the authority to issue up to 10,000,000 shares of preferred stock and to determine the price, rights, preferences, privileges and restrictions, including voting rights, of those shares without any further vote or action by the stockholders. The rights of the holders of common stock may be subject to, and may be adversely affected by, the rights of the holders of any preferred stock that may be issued in the future. The issuance of preferred stock may have the effect of delaying, deferring or preventing a change of control of Yahoo! without further action by the stockholders and may adversely affect the voting and other rights of the holders of common stock. We have no present plans to issue shares of preferred stock. Further, certain provisions of our charter documents, including provisions eliminating the ability of stockholders to take action by written consent and limiting the ability of stockholders to raise matters at a meeting of stockholders without giving advance notice, may have the effect of delaying or preventing changes in control or management of Yahoo!, which could have an adverse effect on the market price of our stock. In addition, our charter documents do not permit cumulative voting, which may make it more difficult for a third party to gain control of our Board of Directors.


DISTRIBUTION OF SECURITIES

    The 7,500,000 shares of Yahoo! Common Stock covered by this prospectus are available for use in connection with acquisitions by us of other businesses, assets or securities. The consideration offered by us in such acquisitions, in addition to any shares of common stock offered by this prospectus, may include cash, certain assets and/or assumption by Yahoo! of liabilities of the businesses, assets or securities being acquired. The amount and type of consideration we will offer and the other specific terms of each acquisition will be determined by negotiations with the owners or controlling persons of the businesses, assets or securities to be acquired after taking into account the current and anticipated future value of such businesses, assets or securities, along with all other relevant factors. The shares of common stock issued to the owners of the businesses, assets or securities to be acquired normally are valued at a price reasonably related to the market value of such common stock either at the time an agreement is reached regarding the terms of the acquisition or upon delivery of the shares.

    We may also permit individuals or entities who have received or will receive shares of our common stock in connection with the acquisitions described above, or their transferees or successors-in-interest, to use this prospectus to cover their resale of such shares. See "Selling Stockholders," as it may be amended or supplemented from time to time, for a list of those individuals or entities who are authorized to use this prospectus to sell their shares of Yahoo! Common Stock.


SELLING STOCKHOLDERS

    The selling stockholders listed in any supplement to this prospectus, and any transferees or successors-in-interest to those persons, may from time to time offer and sell, pursuant to this prospectus, some or all of the shares covered by this prospectus.

    Resales by selling stockholders may be made directly to investors or through a securities firm acting as an underwriter, broker or dealer. When resales are to be made through a securities firm, such securities firm may be engaged to act as the selling stockholder's agent in the sale of the shares by such selling stockholder, or the securities firm may purchase shares from the selling stockholders as principal and thereafter resell such shares from time to time. The fees earned by or paid to such securities firm may be the normal stock exchange commission or negotiated commissions or underwriting discounts to the extent permissible. In addition, such securities firm may effect resales through other securities dealers, and customary commissions or concessions to such other dealers may be allowed. Sales of shares may be at negotiated prices, at fixed prices, at market prices or at prices related to market prices then prevailing. Any such sales may be made on The Nasdaq National Market, in the over-the-counter market, by block trade, in special or other offerings, directly to investors or through a securities firm acting as agent or principal, or

16

a combination of such methods. Any participating securities firm may be indemnified against certain liabilities, including liabilities under the Securities Act. Any participating securities firm may be deemed to be an underwriter within the meaning of the Securities Act, and any commission earned by such firm may be deemed to be underwriting discounts or commissions under the Securities Act.

    In connection with resales of the shares sold hereunder, a prospectus supplement, if required, will be filed under Rule 424(b) under the Securities Act, disclosing the name of the selling stockholder, the participating securities firm, if any, the number of shares involved, any material relationship the selling stockholder may have with us or our affiliates, and other details of such resale to the extent appropriate. Information concerning the selling stockholders will be obtained from the selling stockholders.

    Stockholders may also offer shares of stock issued in past and future acquisitions by means of prospectuses under other available registration statements or pursuant to exemptions from the registration requirements of the Securities Act, including sales which meet the requirements of Rule 145(d) under that Act, and stockholders should seek the advice of their own counsel with respect to the legal requirements for such sales.


LEGAL MATTERS

    The validity of the common stock offered hereby has been passed upon for Yahoo! by Venture Law Group, A Professional Corporation, Menlo Park, California, counsel to Yahoo!.


EXPERTS

    The financial statements incorporated in this prospectus by reference to the Annual Report on Form 10-K of Yahoo! Inc. for the year ended December 31, 1999, have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, independent accountants, given on the authority of said firm as experts in auditing and accounting.


WHERE YOU CAN FIND MORE INFORMATION

    This prospectus is part of a Registration Statement on Form S-4 that we filed with the Securities and Exchange Commission. Certain information in the Registration Statement has been omitted from this prospectus in accordance with the rules of the SEC. We file annual, quarterly and special reports, proxy statements and other information with the SEC. You can inspect and copy the Registration Statement as well as reports, proxy statements and other information we have filed with the SEC at the public reference room maintained by the SEC at 450 Fifth Street, NW, Washington, D.C. 20549, and at the following Regional Offices of the SEC: Seven World Trade Center, New York, New York 10048, and Northwest Atrium Center, 500 West Madison Street, Chicago, Illinois 60661. You can obtain copies from the public reference room of the SEC at 450 Fifth Street, NW, Washington, D.C. 20549 upon payment of certain fees. You can call the SEC at 1-800-732-0330 for further information about the public reference room. We are also required to file electronic versions of these documents with the SEC, which may be accessed through the SEC's World Wide Web site at http://www.sec.gov. Our common stock is quoted on The Nasdaq National Market. Reports, proxy and information statements and other information concerning Yahoo! Inc. may be inspected at The Nasdaq Stock Market at 1735 K Street, NW, Washington, D.C. 20006.

    The SEC allows us to "incorporate by reference" certain of our publicly-filed documents into this prospectus, which means that information included in these documents is considered part of this prospectus. Information that we file with the SEC subsequent to the date of this prospectus will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings made with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, during the effectiveness of this Registration Statement.

17

    The following documents filed with the SEC are incorporated by reference in this prospectus:

    We will furnish without charge to you, on written or oral request, a copy of any or all of the documents incorporated by reference, other than exhibits to such documents. You should direct any requests for documents to Andrea Klipfel, Investor Relations, 3420 Central Expressway, Santa Clara, California 95051, telephone: (408) 731-3300.


FORWARD-LOOKING STATEMENTS

    This prospectus and the documents that are and will be incorporated into this prospectus contain forward-looking statements that involve risks and uncertainties. The outcome of the events described in these forward-looking statements is subject to risks and actual results could differ materially. These statements relate to our future plans, objectives, expectations and intentions. These statements may be identified by the use of words like "believes," "expects," "may," "will," "should," "seeks," "pro forma," or "anticipates," and similar expressions. Our actual results could differ materially from those discussed in these statements. Factors that could contribute to these differences include those discussed under "Risk Factors," beginning on page 3 and elsewhere in this prospectus and documents incorporated herein by reference.

18


PART II
INFORMATION NOT REQUIRED IN PROSPECTUS

Item 20. Indemnification of Directors and Officers.

    Section 145 ("Section 145") of the General Corporation Law of the State of Delaware (the "DGCL") permits a corporation, under specified circumstances, to indemnify its directors and officers against expenses (including attorneys' fees) and other liabilities actually and reasonably incurred by them as a result of any suit brought against them in their capacity as a director or officer, if they acted in good faith and in a manner they reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, if they had no reasonable cause to believe their conduct was unlawful. Section 145 also provides that directors and officers may also be indemnified against expenses (including attorneys' fees) incurred by them in connection with a derivative suit by the corporation if they acted in good faith and in a manner they reasonably believed to be in or not opposed to the best interests of the corporation, except that no indemnification may be made, unless otherwise determined by the court, if such person was adjudged liable to the corporation.

    Article XII of Yahoo!'s Amended and Restated Certificate of Incorporation and Article VI of Yahoo!'s Bylaws authorize indemnification of Yahoo!'s directors and officers to the extent and under the circumstances permitted by the DGCL. Yahoo! has also entered into agreements with its directors and certain officers that will require Yahoo!, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers to the fullest extent not prohibited by law.

    The above discussion of the DGCL and of Yahoo!'s Amended and Restated Certificate of Incorporation, Bylaws and indemnification agreements is not intended to be exhaustive and is qualified in its entirety by such statutes, Amended and Restated Certificate of Incorporation, Bylaws and indemnification agreements.

    Yahoo! maintains liability insurance for the benefit of its officers and directors.

Item 21. Exhibits and Financial Statement Schedules.


Exhibit
No.
   Description
5.1   Opinion of Venture Law Group, A Professional Corporation
23.1   Consent of PricewaterhouseCoopers LLP, Independent Accountants
23.2   Consent of Venture Law Group, A Professional Corporation (included in Exhibit 5.1)
24.1   Powers of Attorney (set forth in the signature page hereto)

    Schedules for which provision is made in the applicable accounting regulations of the Securities and Exchange Commission are either not required under the related instructions, are inapplicable or not material, or the information called for thereby is otherwise included in the financial statements incorporated by reference and therefore has been omitted.

II-1

Item 22. Undertakings.

II-2

II-3


SIGNATURES

    Pursuant to the requirements of the Securities Act of 1933, as amended, Yahoo! Inc. has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Santa Clara, State of California, on August 11, 2000.

    YAHOO! INC.
 
 		  
 		  
 By:		  
/s/ SUSAN DECKER   
Susan Decker
 Senior Vice President, Finance and
Administration, and Chief Financial Officer

POWER OF ATTORNEY

    KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Timothy Koogle and Susan Decker, jointly and severally, his or her true and lawful attorneys-in-fact, each with full power of substitution, for him or her in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement and any other registration statement for the same offering filed pursuant to Rule 462 under the Securities Act of 1933, and to file the same, with all exhibits thereto and all documents in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or any of them, or his or their substitute or substitutes, may lawfully do or cause to be done or by virtue hereof.

    Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement has been signed by the following persons in the capacities and on the dates indicated.

Name and Signature
   Title
   Date
 
 		  
 		  
 		  
 		  
 
/s/ TIMOTHY KOOGLE   
Timothy Koogle		   Chairman of the Board and Chief Executive Officer (Principal Executive Officer)   August 11, 2000
 
/s/ JEFF MALLETT   
Jeff Mallett		  
 		  
President, Chief Operating Officer and Director		  
 		  
August 11, 2000
 
/s/ SUSAN DECKER   
Susan Decker		  
 		  
Senior Vice President, Finance and Administration, and Chief Financial Officer (Principal Executive Officer)		  
 		  
August 11, 2000
 
/s/ JAMES J. NELSON   
James J. Nelson		  
 		  
Vice President, Finance (Chief Accounting Officer)		  
 		  
August 11, 2000
 
/s/ ERIC HIPPEAU   
Eric Hippeau		  
 		  
Director		  
 		  
August 11, 2000
 
/s/ ARTHUR H. KERN   
Arthur H. Kern		  
 		  
Director		  
 		  
August 11, 2000
 
/s/ MICHAEL MORITZ   
Michael Moritz		  
 		  
Director		  
 		  
August 11, 2000
 
/s/ JERRY YANG   
Jerry Yang		  
 		  
Director		  
 		  
August 11, 2000
 
 		  
 		  
 		  
 		  
 

II-4


INDEX TO EXHIBITS

Exhibit
Number
   Description
5.1   Opinion of Venture Law Group, A Professional Corporation
23.1   Consent of PricewaterhouseCoopers LLP, Independent Accountants
23.2   Consent of Venture Law Group, A Professional Corporation (included in Exhibit 5.1)
24.1   Power of Attorney (set forth in the signature page hereto)

QuickLinks

TABLE OF CONTENTS
YAHOO!
RISK FACTORS
DISTRIBUTION OF SECURITIES
SELLING STOCKHOLDERS
LEGAL MATTERS
EXPERTS
WHERE YOU CAN FIND MORE INFORMATION
FORWARD-LOOKING STATEMENTS
PART II INFORMATION NOT REQUIRED IN PROSPECTUS
SIGNATURES
POWER OF ATTORNEY
INDEX TO EXHIBITS
Prepared by MERRILL CORPORATION www.edgaradvantage.com QuickLinks -- Click here to rapidly navigate through this document

Exhibit 5.1


OPINION OF COUNSEL
August 11, 2000

Yahoo! Inc.
3420 Central Expressway
Santa Clara, CA 95051

Ladies and Gentlemen:

    We have examined the Registration Statement on Form S-4 to be filed by you with the Securities and Exchange Commission (the "Commission") on August 11, 2000 (the "Registration Statement"), in connection with the registration under the Securities Act of 1933, as amended, of 7,500,000 shares of your Common Stock (the "Shares"). As your counsel in connection with this transaction, we have examined the proceedings taken and are familiar with the proceedings proposed to be taken by you in connection with the issuance of the Shares.

    It is our opinion that upon conclusion of the proceedings being taken or contemplated by us, as your counsel, to be taken prior to the issuance of the Shares, and upon completion of the proceedings being taken in order to permit such transactions to be carried out in accordance with the securities laws of the various states where required, the Shares when issued in the manner described in the Registration Statement will be legally and validly issued, fully paid and non-assessable.

    We consent to the use of this opinion as an exhibit to said Registration Statement, and further consent to the use of our name wherever appearing in said Registration Statement, including the prospectus constituting a part thereof, and in any amendment or supplement thereto.


QuickLinks

OPINION OF COUNSEL August 11, 2000
Prepared by MERRILL CORPORATION www.edgaradvantage.com QuickLinks -- Click here to rapidly navigate through this document

Exhibit 23.1


CONSENT OF INDEPENDENT ACCOUNTANTS

    We hereby consent to the incorporation by reference in this Registration Statement on Form S-4 of Yahoo! Inc. of our report dated January 7, 2000, except as to the stock split described in Note 1 and Note 11, which are as of March 9, 2000, relating to the financial statements and financial statement schedule, which appears in Yahoo! Inc.'s Annual Report on Form 10-K for the year ended December 31, 1999. We also consent to the reference to us under the heading "Experts" in such Registration Statement.

/s/ PricewaterhouseCoopers LLP
San Jose, California
August 10, 2000


QuickLinks

CONSENT OF INDEPENDENT ACCOUNTANTS