Credit Suisse Group after the explosion of Archegos Capital Management caused it to lose $4.7 billionFinancing terms for hedge funds and family offices are being tightened, which could herald new industry practices.

Credit Suisse is already calling clients to change the margin requirements in the swap agreement to comply with the stricter terms of its prime broker agreement, according to people familiar with the matter. Specifically,Credit Suisse is shifting from static margin to dynamic margin, which could force clients to provide more collateral and may reduce the profitability of some transactions.

A spokesman for Credit Suisse could not be reached for comment.

It was this swap arrangement that Bill Hwang used to hold highly leveraged stock positions in its family's office, Archegos. When the market value of its position suddenly shrank in the week of March 22nd, Archegos's margin and stock went up in smoke, and Hwang lost $20 billion in just a few days.

Static margin sets a fixed amount of collateral that a client must pay for holding a specific number of positions. Through dynamic margin, if the potential risk of a position or account increases due to factors such as volatility or concentration, the broker can ask for more collateral.

Typically, the margin period locked in the swap agreement by the customer is 60 or 180 days. Credit Suisse is asking some customers to adopt the new terms immediately, according to a person familiar with the matter.

The move could herald tighter financing conditions for hedge funds and family offices.The three banks that do business with Archegos disclosed a total of $7 billion in losses, which JPMorgan analysts estimate could total $10 billion.

Separately, Sherrod Brown, chairman of the Senate Banking Committee, released letters he wrote this week to banks involved in the Archegos explosion, asking them to disclose more details of the deal with the Bill Hwang family office.

In addition to Credit Suisse and Nomura, which reported losses of billions of dollars, Goldman Sachs and Morgan Stanley also received the letter.

In the letter, Brown also compared the Archegos incident with events that affected market stability, such as long-term Capital Management, and said that excessive leverage combined with negligence in risk control would pose a threat to investors.

Brown focuses on banks disclosing customer acquisition and KYC review processes related to the family office business and explaining how to determine the type, leverage and collateral ratio of services provided.

The Archegos,Brown also requires the relevant banks to disclose the process of accepting them as customers, and whether bank regulators or risk control committees have approved it, especially how the settlement of Bill Hwang's insider trading charges by the US SEC in 2012 affected the decisions of the banks concerned.