After Microsoft’s move of signing a deal to partner in search, the U. S. residents have started shifting their search engine use from Yahoo to Microsoft, since mid-2009.

As a result, Yahoo's share of U. S. search queries has reportedly dropped to 17 percent, in January, from 17.3 percent, in December, while Microsoft's share jumped from 10.7 percent to 11.3 percent.

Prior to the launch of Bing and the signing of the search deal, Yahoo had a 20.4 percent share of queries, while Microsoft's was 8.2 percent.

Admitting that the search advertising remains a very important revenue stream for the company, the Yahoo officials have shared that the company intends to outsource the back-end search functions to Microsoft.

Microsoft’s 10-year search deal instigates Yahoo's to enhance its search properties and also be in charge of selling search ads. In exchange, Microsoft will share revenue for ads monetized on Yahoo search sites and on those of Yahoo's search network partners.

It may enable yahoo to retain, and ideally grow, search traffic on its sites, now and when the Microsoft deal kicks in.

As per yahoo’s estimation in July, the search deal would boost its annual operating income by about US$500 million. It will also provide capital expenditure savings of about $200 million and will its increase annual operating cash flow by about $275 million.