The U.S. Security and Exchange Commission (SEC) is examining the collapse of Bill Hwang’s Archegos capital management, whether the firm engaged in market manipulation. SEC is currently reviewing the firm’s trading activity, including whether it concealed the size of its bets on public companies. Archegos were recently summoned with a subpoena, according to people familiar with the matter. The authorities are examining whether Archegos bought multiple stakes in the same companies across several banks to avoid triggering public disclosure rules.

Archegos amassed a concentrated portfolio of stocks well in excess of $100 billion by using borrowed money. Unfortunately, some of the stocks tumbled in March, triggering margin calls from banks, which then dumped Hwang’s holdings. Lenders including Credit Suisse Group AG, Nomura Holdings Inc., and Moran Stanley lost more than $10billions. This prompted internal investigations and the forced departures of senior executives. Meanwhile, regulators are discussing whether revise rules exempting family offices like Hwang’s from stricter oversight. In May, SEC chairman Gary Gensler told congress that more stringent disclosure laws may be warranted for investment firms after the Archegos debacle. He later signaled plans to make more industry data publicly available. It is worth noting that the opening of a SEC probe is only a preliminary step and doesn’t mean Hwang, who hasn’t been accused of wrongdoing, will face enforcement action.