SAN FRANCISCO - Billionaire investor Carl Icahn is reportedly loading up on Yahoo's stock in preparation for a possible attempt to shove aside the Internet icon's board and bring the company's disillusioned suitor, Microsoft, back to the bargaining table.

As he mulls whether to lead a rebellion, Icahn has accumulated about 50 million Yahoo shares, a stake of roughly 3.6 percent in the company, CNBC and The Wall Street Journal reported.

Icahn faces a Thursday deadline to submit an alternate slate of directors to oppose Yahoo's board at the company's July 3 annual meeting.

Yahoo representatives declined to comment about a possible showdown with Icahn.