An arrangement requiring Microsoft to pay Yahoo! a minimum amount per search on Yahoo!'s website expired March 31. That had raised concerns Yahoo might make less money from the Microsoft partnership.
Those worries eased Tuesday with a regulatory filing that disclosed Microsoft is maintaining the revenue-per-search guarantee through March 2014.
Yahoo!'s stock gained 86 cents, or 3.4 percent, to $26.03 in afternoon trading. It's the first time the stock has been above $26 in nearly five years.
Under a 10-year alliance that began in 2010, Microsoft provides its search technology to Yahoo! in exchange for 12 percent of the revenue from search ads on Yahoo!'s site.