Yahoo will be able to quit the deal if it misses certain targets
Yahoo will be able to quit its internet search deal with Microsoft if it fails to meet certain market share and revenue targets.
Yahoo can abandon the deal if Microsoft does not produce advertising revenue per search within a certain - undisclosed - percentage of Google's.
It can also walk away if the share of search queries falls below a certain percentage of the market.
Fresh details of the deal emerged in a regulatory filing late on Tuesday.
Microsoft will pay Yahoo $50m a year for the first three years of the deal to cover unforeseen transition costs.
Yahoo can keep 88% of the net revenues from advertisements placed on its pages for five years and between 83% and 93% of the revenue for the remaining five years.
Microsoft will hire about 400 workers from Yahoo.
Yahoo has been struggling to make profits in recent years. Last year, it rebuffed several takeover bids from Microsoft in an attempt to go it alone.
The deal, announced last month, is designed to help the two companies take on Google, its chief rival, which has a market share of about 65%.
Under the deal, Microsoft's Bing search engine will power the Yahoo website and Yahoo will in turn become the advertising sales team for Microsoft's online offering.