NEW YORK (AP) — Facebook's battered stock closed lower Tuesday, erasing some of the gains it saw a day earlier.

Regulatory filings revealed Monday after the stock market closed that Peter Thiel, Facebook's first big investor, shed most of his holdings in the social networking icon. Thiel is also a board member.

Thiel originally invested $500,000 in Facebook in 2004. He sold 16.8 million shares in the company's May 18 IPO and another 20 million or so late last week after a lockup period banning the sales expired. In all, he's reaped more than $1 billion from the sales.

On Monday, Facebook's shares hit a new low of $18.75 before bouncing back to $20.01 by the time the market closed. But Tuesday saw the stock dip 85 cents, 4.3 percent, to close at $19.16.