Icahn has led proxy fights at companies such as Motorola Inc. and drugmaker ImClone Systems Inc., frequently pushing them to sell part or all of their businesses to help revive sagging share prices. Today he urged Yahoo to make a deal with Microsoft, saying the combination "is by far the most sensible path" if they want to take on Google Inc. "The board of directors of Yahoo has acted irrationally and lost the faith of shareholders and Microsoft," Icahn, 72, said in a letter to Yahoo's board. "I sincerely hope you heed the wishes of your shareholders and move expeditiously to negotiate a merger with Microsoft, thereby making a proxy fight unnecessary." Yahoo, based in Sunnyvale, California, climbed 39 cents, or 1.4 percent, to $27.53 at 10:11 a.m. New York time in Nasdaq Stock Market trading. The stock had fallen 32 percent in the year before Microsoft's bid. Microsoft, the world's biggest software maker, gained 3 cents to $29.96.