NEW YORK (CNNMoney) -- The Securities and Exchange Commission is investigating one of the nation's largest hedge funds, SAC Capital Advisors LP, in connection with insider trading, according to a published report.
The Wall Street Journal reported Wednesday that the SEC is looking into whether traders at SAC profited from inside information related to a 2007 merger in the health care industry.
SAC, run by Steven A. Cohen, is one of several hedge funds being investigated for trading in the stocks of health care companies involved in mergers and acquisitions over the last decade, according to the newspaper.
The Journal said authorities have not accused SAC or Cohen of any wrongdoing.
SAC did not respond to repeated requests for comment. But a spokesman told the Journal that the fund is cooperating with the inquiry and is "confident in our business practices."
In addition to the SEC inquiry, SAC is also being investigated by federal prosecutors in New York and Sen. Charles Grassley, an Iowa Republican, the Journal said.
The SEC and the U.S. Attorney's Office in New York declined to comment.
The Connecticut-based hedge fund manages over $16 billion, according to regulatory filings. Since it was founded in 1992, SAC's lightning-fast trading strategies have made it a one of Wall Street's biggest players.
SAC has been seen as a prize in the government's recent crackdown on insider trading, which brought down hedge fund manager Raj Rajaratnam earlier this year.
Investigators have already nabbed some former SAC money managers in separate insider trading cases, and one well-known investor in the fund has already defected because of the multiple inquires.
According to the report, the SEC is looking into investments SAC made in MedImmune, an Australian biotech firm, in the months before it was bought by AstraZeneca for $15 billion.
AstraZeneca (AZN) did not respond to requests for comment.
The Journal outlined purchases of MedImmune stock that SAC and affiliated funds made in early 2007, amid speculation that a deal was in the works with AstraZeneca. After the takeover was officially announced on April 23, 2007, shares of MedImmune surged 18%.
SAC is also the focus of a criminal probe by federal investigators in New York, according to the Journal. That probe reportedly involves trades in a fund overseen by Cohen that were recommended by former SAC traders who have since pleaded guilty to insider trading.
In yet another inquiry, Sen. Grassley last week sent a letter to the SEC requesting information on referrals the commission has received from the Financial Industry Regulatory Authority, an industry watchdog.
Grassley is looking for details on whether any SAC traders received a Wells Notice, or an official warning that they are being investigated by the agency, among other things.
Calls and e-mails to Grassley's office were not returned. 
