San Francisco - Billionaire investor Carl Icahn has amassed some 50 million shares in Yahoo as he prepares to mount a proxy fight aimed at reviving Microsoft's thwarted takeover bid for the internet portal, The Wall Street Journal reported late Tuesday.

Icahn's stake represents 3.6 per cent of the Silicon Valley company, which rejected Microsoft's 47.5-billion-dollar bid earlier this month. That move was widely castigated by Yahoo shareholders, who could have had a premium of more than 65 per cent on the company's share price before the bid was announced.

Icahn wishes to oust the Yahoo board at the company's annual meeting on July 3 and appoint new directors amenable to Microsoft's offer. His deadline for naming alternative candidates for the board is Thursday.

Icahn, one of America's most skilful corporate raiders, is especially adept at buying stakes in troubled companies and forcing them to reorganize or sell. Among his most recent successes are Blockbuster Inc, Motorola Inc and BEA Systems.

News of the Icahn strategy ignited a surge in late trading Tuesday in Yahoo shares, which closed up 5.2 per cent to finish at 26.56 dollars, still far below the 33 dollars per share offered by Microsoft. (dpa)