Billionaire investor Carl Icahn reportedly is snapping up Yahoo stock in preparation for a possible attempt to replace the Internet company’s board after the directors turned down Microsoft’s $47.5 billion takeover offer.

Icahn has bought as many as 50 million Yahoo shares, both CNBC and The Wall Street Journal reported Tuesday. That would give Icahn a 3.6 percent stake in the Internet pioneer.

The financier, who didn’t immediately return calls seeking comment, is known for shaking up slumping companies. He could spearhead a campaign to oust Yahoo’s 10 directors for not accepting Microsoft Corp.’s final offer of $33 per share.

The deadline for nominating an alternate slate of directors to Yahoo’s board is Thursday.