(Corrects spelling of Commission in first paragraph)
By Ankur Banerjee and Carl O'Donnell
Feb 29 (Reuters) - Shares in Valeant Pharmaceuticals International Inc fell as much as 21 percent on Monday after the embattled drugmaker revealed that it was under investigation by the U.S. Securities and Exchange Commission.
"Valeant confirms that it has several ongoing investigations, including investigations by the U.S. Attorney's Offices for Massachusetts and the Southern District of New York, the SEC, and Congress," said Laurie Little, a Valeant spokeswoman.
She said the company confirmed that it "received a subpoena from the SEC in the fourth quarter of 2015 and, in the normal course, would have included this disclosure in its 2015 10-K. We do not have further detail to provide at this time."
The SEC probe is separate from an existing investigation into a company purchased last year by Valeant, Salix Pharmaceuticals Ltd, according to a person familiar with the matter.
News of the probe came a day after the Canadian company canceled the release of fourth-quarter earnings, withdrew 2016 financial guidance and said its chief executive had returned from medical leave.
The company's U.S.-traded shares fell 18.4 percent to close at $65.80 per share.
The stock has been see-sawing for the past month, often gaining or losing 5 percent or more in intraday trading, as speculation has swirled about its future.
The timing of the return of CEO Pearson had been unknown after suffering from severe pneumonia, and there was speculation on Wall Street on whether he would return at all.
The full outcome of its board investigation into the relationship with pharmacy Philidor RX Services, now terminated, remained unknown.
Investors have questioned how the company will regain sales of many dermatological products that Philidor sold, and do not know the terms of a new distribution agreement with Walgreens Boots Alliance Inc.
Last week, the company said it would restate earnings to reflect preliminary findings from the board review, adding that it should have accounted for $58 million of revenue later than it did.
The company also said it would delay filing its quarterly results, and had set Monday for releasing unaudited results to Wall Street. A conference call to discuss quarterly earnings was also canceled.
On Sunday night, the company canceled the Monday presentation and said its CEO had returned from a two-month medical leave.
Moody's Investors Service placed the ratings of Valeant under review for downgrade, reflecting concerns that the company's operating performance is weaker than its expectations. (bit.ly/1T4m6Pl) (Reporting by Carl O'Donnell in New York and Ankur Banerjee in Bengaluru; additional reporting by Caroline Humer in New York; Editing by Jeffrey Benkoe, Maju Samuel and David Gregorio)