The defendants are accused of having schemed earlier that day to manipulate the stock price of a Drexel client.

Mr. Solomon would be the first Drexel client to agree to cooperate.

It was not immediately clear whether any Drexel clients might drop the firm as financial adviser.

He added that he understood other Drexel clients had received similar subpoenas for information.

But rivals are finding it harder to pick off Drexel clients than they had expected.

The Drexel clients would subsequently have to buy the bonds on the secondary market at a higher price, providing substantial profits to the partnerships.

The best known was the debt portfolio of the insurer Executive Life, a former Drexel client.

The testimony had damaging effects on some former Drexel clients, however.

The second allegation was that Drexel's executives received higher prices than Drexel clients when they sold these junk bonds.

According to the documents provided at the hearing, the partnerships included Drexel clients as well as executives.