A $7 billion hedge fund says it's being investigated by the SEC and the US Department of Justice

Visium Asset Management, the $7 billion healthcare-focused hedge fund, told investors in a letter that it's being investigated by the US Department of Justice and the US Securities and Exchange Commission (SEC).

The fund's founder, Jacob Gottlieb, wrote in a March 7 letter:

They have requested information from several years ago regarding the valuation of certain securities in the firm's credit fund which was closed in 2013. Additionally, they have requested information regarding the trading of certain securities, including the use of a consultant who stopped providing services to the firm in 2011. We are providing the requested information to the Government.

Gottlieb also wrote that the company is unable to discuss the specifics of the investigations while they are ongoing.

Visium was founded in 2005. The firm employs 170 people with offices in New York, London, and San Francisco.

"We expect only the highest ethical conduct from all our employees," the letter said.

A Visium spokesman declined to comment beyond the letter.

The Wall Street Journal's Gregory Zuckerman first reported the news.