Will antitrust probe keep Microsoft, Yahoo apart?

WASHINGTON -- Yahoo and Microsoft hope that by joining forces, they can tilt the balance of power in Internet search away from Google. First, however, Yahoo and Microsoft have to convince regulators that their plan won't hurt online advertisers and consumers.

As the U.S. Justice Department reviews the proposed partnership, approval figures to hinge on this question: Will the online ad market be healthier if Google's dominance is challenged by a single, more muscular rival instead of two scrawnier foes?

The first step toward getting an answer came this month when Microsoft and Yahoo filed paperwork with federal regulators to comply with the Hart-Scott-Rodino Act, an antitrust law governing mergers and alliances between competitors. The Justice Department has until early September to approve the agreement or — as is likely in this case — request additional information.

European regulators are also expected to review the deal. Microsoft and Yahoo are bracing for the probes to extend into early next year, and the outcome is far from certain.

Just nine months ago, Google abandoned its own proposed partnership with Yahoo to avoid a showdown with the government, which had concluded that Google was already too powerful in the lucrative market for selling ads alongside search results.

Google had hoped to extend its reach even further by selling ads next to some of Yahoo's search results, and in the process, keep Yahoo out of Microsoft's clutches. Microsoft aggressively lobbied against the partnership.

With the Google-Yahoo inquiry behind them, U.S. antitrust regulators are likely to enter this examination with a clearer definition of the Internet search landscape and a better understanding of how it affects the steadily growing online advertising market.

Justice Department spokeswoman Gina Talamona would not comment on the antitrust review, whose existence was confirmed by Microsoft and Yahoo.

Microsoft is counting on the Yahoo partnership to close the wide gap separating the software maker from Google in search. Under the 10-year agreement announced last month, Microsoft's Bing search engine would process all search requests and steer search-related ads on Yahoo.