"This is impressive," Charles E. Grassley, the Republican senator from Iowa, said, admiring the futures trading firm's state-of-the-art facility. "This is a company that's on the top of things."

Today, the only impressive thing about Peregrine is the depth of its problems. After a suicide attempt by its founder on Monday, regulators discovered about $215 million in customer money was missing. The Commodity Futures Trading Commission filed a lawsuit charging fraud. Criminal authorities are investigating. Peregrine has filed for bankruptcy and shut down.

As the founder Russell Wasendorf lies in critical condition in an Iowa City hospital, Peregrine's angry customers are asking, How could futures industry regulators have missed another potential fraud? The scandal comes just months after MF Global, the defunct futures brokerage firm, lost more than $1 billion in clients' money.

It now appears that regulators missed the red flags for years.

In 2004, a Peregrine client sent a letter to the National Futures Association, the firm's primary regulator, and the C.F.T.C., asking it to intervene to prevent the firm from misusing its customers' money, according to a person with knowledge of the correspondence and a copy of the letter obtained by The New York Times. Five years later, a tipster wrote to the N.F.A. asking it to review Peregrine's bank account information for accuracy, according to people briefed on the matter who spoke on the condition of anonymity because the investigation was private. The tip was anonymous, and it is unclear how seriously the N.F.A. took it.

The auditor for Peregrine was a one-person shop run out of the accountant's home in Glendale Heights, Ill., a Chicago suburb. As part of its investigation, the C.F.T.C. is looking into the role that the individual played, according to a person with knowledge of the case.

After the collapse of MF Global, the C.F.T.C. ordered a review of all futures firms to ensure the safety of customer money. The N.F.A. — where Mr. Wasendorf serves on an advisory committee — gave Peregrine a clean bill of health in January.

Government regulators are examining whether Mr. Wasendorf doctored bank statements provided to the N.F.A., according to people briefed on the matter who were not authorized to speak publicly because of the investigation. Authorities are also expected to question officials at U.S. Bank, which held the client's money.

"The entire industry is outraged that it happened the first time, let alone a second time," said Michael V. Dunn, a former commission of the C.F.T.C., referring to the collapse of two brokerages. "We need to do something about this."

The N.F.A. declined to comment. Calls to Peregrine's auditor were not immediately returned.

For Tom Power, a former MF Global broker, it is hard not to take the brokerage scandals personally.

After losing his job when MF Global went bust, Mr. Power, 31, started his own business. He has spent the last eight months signing up clients still circumspect about their losses at MF Global. For his new venture, he chose to clear his trades through Peregrine, which is commonly known as PFGBest.

"The customers are just heartbroken over what happened," Mr. Power said. "To have to call these same guys that were with me at MF and tell them it happened again? It's just devastating."

Futures firms like Peregrine match buyers and sellers of contracts for commodities like wheat and oil, charging a thin commission for the service. Farmers and others use such contracts to protect themselves from large price fluctuations.

Speculators also play the futures market and they, too, have been burned. Mark Tucker, a part-time investor, has had the misfortune of dealing with both MF Global and PFGBest.

"You're prepared to take risks," said Mr. Tucker, who lost about $80,000 between the two firms. "But you don't expect risks to come from money being stolen out of your account."