FILE PHOTO: The seal of the U.S. Securities and Exchange Commission hangs on the wall at SEC headquarters in Washington, U.S., June 24, 2011. REUTERS/Jonathan Ernst/File Photo

(Reuters) - Online retailer Overstock.com Inc OSTK.O said on Thursday the U.S. Securities and Exchange Commission was investigating its blockchain platform tZERO and its cryptocurrency.

Overstock said it would cooperate with the SEC and was responding to the agency’s request for documents.

Shares of the company fell 8 percent to $55.65 on Thursday morning.