The firm clearly had the expertise — it was a leader in underwriting and trading bonds and esoteric securities backed by mortgages. In addition, Ralph R. Cioffi, who ran the funds, had played a major role in building the Bear Stearns mortgage business.

So, in August, the Bear Stearns High-Grade Structured Credit Enhanced Leveraged Fund — the second fund that eventually had huge losses — was started with $600 million in investments, mostly from wealthy individual clients of Bear Stearns, and at least $6 billion in money borrowed from banks and brokerage firms. Bear Stearns and a handful of its top executives invested a mere $40 million in both funds.

The timing could not have been worse.

By the end of last year, housing prices in many areas were cresting and beginning to fall. The decline began to expose lax lending standards in the subprime market. Soon borrowers started falling behind on payments just months after they closed on their loans, forcing several large lenders into bankruptcy protection.

The Bear Stearns funds, like so many others, had invested in collateralized debt obligations, or CDOs, which invest in bonds backed by hundreds of loans and other financial instruments. Wall Street sells CDOs in slices to investors. Some of those pieces have low yields but they are easily traded and carry less risk; others are more susceptible to defaults and trade infrequently, which makes them difficult to value.

Last year, $316.4 billion in mortgage-related CDOs were issued, about 77 percent more than the year before, the Securities Industry and Financial Markets Association said.

At first, the Bear Stearns hedge funds appeared to weather the storm. But in March, the older fund registered its first loss. One investor, who asked not to be identified because he was trying to recover his investment, said that when he moved to get his money out, he was told investors had tried to redeem 10 percent of the fund.

By April, the older fund was down by 5 percent for the year, and the newer fund had fallen 10 percent.