Microsoft Corp. has finally reached a long-sought and expensive goal – its Bing search engine now ranks second behind Google in the Internet’s most lucrative market. Bing and Microsoft’s other websites fielded 2.75 billion search requests in the U.S. during December, catapulting in front of Yahoo Inc. for the first time in the jockeying for runner up to Google Inc., according to statistics released Wednesday by comScore Inc. Bing’s December volume translated into a 15.1 percent share of the U.S. search traffic, comScore said. Yahoo processed 2.65 billion search requests, representing 14.5 percent of the U.S. market. Google remained Internet’s go-to place for information, with 12 billion U.S. requests in December. That works out to a 65.9 percent market share. Other research firms track the Internet search market. But comScore’s numbers matter the most to industry analysts and the companies trying to attract queries so they can make more money from the ads that appear alongside the results. Google’s dominance of online search is the main reason it has established itself as the Internet’s most profitable company. Analysts have expected Microsoft and Yahoo to flip-flop their positions in Internet search since they announced a partnership in July 2009. The 10-year agreement has enabled Yahoo to save money by relying on Microsoft to provide the bulk of its search technology. Microsoft wanted the deal so it would have billions more search requests to analyze each year, giving it a better chance to learn about people’s tendencies and preferences.