Microsoft and Yahoo are heading towards signing a deal to collaborate on internet and advertising in bid to challenge Google, reported Bloomberg, citing two people familiar with the matter.

Several top executives from Microsoft including, SVP of the Online Audience Business Group Yusuf Mehdi, search head Satya Nadella and top digital executive Qi Lu, have flown down to Silicon Valley to finalise the deal with Yahoo, according to All Things Digital.

The deal could be announced within the next week, reported All Things Digital citing companies’ sources. It also reported that Yahoo is likely to take the lead in selling premium advertising for the companies.

In February 2008, Microsoft has made a proposal to the Yahoo board to acquire all the outstanding shares of Yahoo common stock for approximately $44.6 billion. However, Yahoo board has rejected that deal. Since then, talks between the two companies have been continuing on and off.

Earlier this month, Microsoft has launched search engine Bing, in a move to challenge Google. According to web analytics firm StatCounter, Bing has secured 8.23% of all the US-based searches in the month of June, up from 7.21% in May.

Microsoft’s gain in the market share is expected to show a positive impact on the software major’s proposal to acquire Yahoo.