said it has received a civil subpoena from the
Securities and Exchange Commission
, indicating that the agency is conducting a formal investigation of the company.
The company, a hospital owner, said last November that the SEC had started an informal inquiry.
The subpoena, which Tenet received Tuesday afternoon, seeks documents going back to May 31, 1997, related to Medicare outlier payments, stop-loss payments and increases in gross charges, as well as the company's financial disclosures.
Tenet said it will supply the SEC with the requested documents and continue to cooperate with securities regulators.
Shares of Tenet closed Tuesday at $12.15 on the
New York Stock Exchange
. The stock was down 3.7% to $11.70 in Instinet premarket trading.
Late last month, Tenet cut its profit and cash-flow estimates, and several analysts and credit agencies offered negatives views on the company. That news followed a review that was designed to evaluate the company's prospects, and turned up a
host of problems at Tenet.