Scott Sacane's legal troubles continued to mount Monday as a second company sued him over his hedge fund's unusual trading activity.

The lawsuit filed Monday in a federal court in Connecticut by

Esperion Therapeutics

(ESPR) - Get Report

seeks to recover any "short-swing" trading profits generated by Sacane and his Durus Capital Management in Esperion's stock. Both Durus and Sacane are named in the complaint.

Esperion is bringing the lawsuit under a seldom-invoked securities law, Section 16-b, that prohibits big holders of a stock from profiting on short-term trades. The complaint doesn't specify how much money the company believes it's entitled to.

"We feel that this lawsuit represents the best course of action to protect the interests of Esperion and its stockholders," said Roger Newton, Esperion's chief executive and president, in a press release.

Sacane's attorney, Matthew Dontzin, could not be reached for comment.

The lawsuit is similar to one filed in the same courthouse two weeks ago by

Aksys

(AKSY)

, another small medical-products company in which Durus compiled a large stake. The Aksys lawsuit also didn't place a dollar value on Durus' short-swing trades.

But the amounts owed to both companies could be significant, given the extent of Durus trading activity in both stocks.

Over the past year, Durus spent about $260 million to acquire huge stakes in Aksys and Esperion. In the month of July, the hedge fund sold millions of shares of both stocks, after they had posted triple-digit percentage gains.

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Last month Sacane belatedly acknowledged in a regulatory filing that his Connecticut hedge fund had acquired a 33% equity stake in Esperion and a 77% equity stake in Aksys. Sacane has insisted he "inadvertently" acquired the shares.

Most on Wall Street have long doubted the explanation and attribute the unusual trading by the purported $400 million hedge fund to either gross incompetence or stock manipulation. Securities regulators also have their doubts: the Boston office of the

Securities and Exchange Commission

opened an inquiry into Durus' trading activity two weeks ago.

Meanwhile,

TheStreet.com

reported previously that another investment fund with close ties to Sacane was selling most of its shares in the same companies during the period Durus was mostly buying them.

Filings with the government show that Perseus, a Washington-based fund headed by investment banker and publishing magnate Frank Pearl, unloaded 1.15 million shares of Esperion and 1.1 million shares of Aksys during the first half of this year.

The selling by Perseus, which claims a number of Washington power brokers, including former U.N. Ambassador Richard Holbrooke, on its board, coincided with the big runup in the prices of both stocks.

The timing of stock trades are of interest because for several years Sacane had been a Perseus portfolio manager and also managed the

Perseus-Soros BioPharmaceutical Fund

, a $400 million joint venture between Perseus and

Soros Fund Management

.