Richard S. Fuld tried for months to persuade Wall Street that Lehman Brothers, the investment bank he runs, could weather the storm in the financial markets. But by last Wednesday his time had run out: Confidence in Lehman seemed to be slipping away.

In the days that followed Mr. Fuld scrambled to secure a financial lifeline for his hard-pressed investment bank and avert the kind of panic that brought down Bear Stearns. The result, announced Monday morning, was $6 billion in fresh capital from an array of blue-chip investors, enough to shore up Lehman, at least for now.

But the news also came with a stunning admission: Lehman Brothers, whose veteran executives pride themselves on their ability to manage risks, lost a staggering $2.8 billion in the second quarter, its first deficit since going public in 1994. The loss far exceeded even the most pessimistic forecasts and reflected a twin blow of soured assets and bad trades.

What is more, hedges that Lehman had put in place to cushion potential losses from mortgage investments went wrong, adding to the red ink, rather than minimizing it. The news heightened fears that other banks might run into more trouble.