In February 2008, as the mortgage meltdown was creating a crisis at Thornburg Mortgage, the chief executive of the big lender wrote an e-mail explaining how he hoped to keep the trouble under wraps, the Securities and Exchange Commission said.

“We don’t want to disclose our current circumstance until it is resolved,” chief executive Larry A. Goldstone allegedly wrote. The aim, Goldstone allegedly added, was “to keep the current situation quiet while we deal with it.”

As it turns out, the problem became too big to contain, the company’s stock price lost 90 percent of its value in two weeks, and Thornburg landed in bankruptcy.

On Tuesday, the SEC cited the e-mail as it charged Goldstone and two other former Thornburg executives, former chief financial officer Clarence Simmons and former chief accounting officer Jane Starrett, with fraud for allegedly trying to hide the company’s deteriorating financial condition.

The executives schemed to overstate the company’s income for the fourth quarter of 2007 by more than $400 million, the SEC alleged. They improperly determined that losses related to mortgage securities were only temporary and therefore did not have to be deducted from earnings, the SEC said.

If the allegations are true, the case is another illustration of how members of the financial industry struggled to conceal the depths of the problem as the nation plunged toward catastrophe.

Last month, the SEC charged that investment bankers and traders at Credit Suisse used fraudulent bookkeeping to avoid recording losses on subprime investments.

In a joint statement, Goldstone and Simmons said they will fight the charges.

“The SEC’s case singles out and punishes us for not having the clairvoyance to anticipate an unprecedented financial system crisis,” they said. “In its zealousness to find people to blame for the financial crisis, the SEC has brought a case based on hindsight that is not supported by the facts, unwinnable in court, and profoundly unfair,” they said.

Thornburg, based in Santa Fe, N.M., was one of the nation’s largest mortgage companies. It issued adjustable-rate loans and invested in loan-backed securities, the SEC said.

To finance its business, it borrowed money using mortgage-
related investments as collateral. When the collateral’s value fell below certain levels, Thornburg was faced with margin calls, which required it to pay down borrowing with cash or post additional collateral.

In the weeks leading up to the filing of its annual report for 2007, Thornburg was beset with margin calls, the SEC said. It met $650 million of them but was unable to meet an additional $300 million in a timely fashion, the SEC said.

According to the SEC, Thornburg executives scrambled to satisfy the margin calls before filing the annual report. Then they learned that more trouble was looming, and they rushed to file their report before they would have to include it, the SEC said.

According to the SEC, Simmons e-mailed Starrett that he had given a company manager a 6 a.m. deadline on a Thursday to file the report, saying, “I do not want there to be any issues based on Thursday activity.”

The report was filed at 4 a.m. local time on Feb. 28, 2008, and by 6 a.m., Thornburg began to receive additional margin calls, the SEC said. The company’s stock dropped.

Alluding to that drop and to a section of the annual report, the SEC said, Simmons sent an e-mail to Goldstone:

“I guess the recent development section did not go over well. If they only knew.”

Two business days later, Thornburg disclosed that it had incurred an additional $270 million of margin calls and was unable to meet most of them, the SEC said. The stock lost half of its value.

The three former executives were also accused of withholding information about the margin calls from the auditors reviewing Thornburg’s financial disclosures.

According to the SEC, in a Feb. 25, 2008, e-mail to the other defendants, Starrett wrote: “We have purposely not told [the auditors] about the margin calls so that we don’t escalate an issue which we believe will be put to rest by the time they have to issue their opinion.”

Attorneys for Starrett did not respond to requests for comment.