Another one-time mortgage high-flier is teetering on the edge.

Impac Mortgage Holdings Inc. said it lost $2.05 billion in 2007 and warned that its survival is in jeopardy.

It also said that the Securities and Exchange Commission is looking at its operations.

“Recent increased delinquencies and losses with respect to residential mortgage loans, may cause us to recognize additional losses, which would further adversely affect our operating results, liquidity, financial condition, business prospects and ability to continue as a going concern,” the company stated in its delayed annual report.

Impac, an Irvine, Calif.-based real estate investment trust, is one of a number of companies that specialized in risky “Alt-A” mortgages, typically provided to individuals with questionable finances.

The company also said that at year-end it had a shareholders’ deficit of $1.1 billion, meaning that total liabilities exceed total assets by that much.

“The existence of a shareholders’ deficit may affect our ability to continue to pay scheduled distributions on our preferred stock, limit our ability to obtain future debt or equity financing, and cause regulatory issues as it could affect our state mortgage licenses,” it warned. “If we are unable to obtain financing in the future, it could have a negative effect on our operations and our liquidity.”