As the financial world reverberates from the collapse of Britain's oldest investment bank, the big question on everybody's mind is why did the 28-year-old trader being blamed for the debacle do it?

Baring Brothers & Co. is now under the control of court-appointed administrators trying to assess what can be salvaged after hundreds of millions of dollars in losses in Asian futures markets ruined the bank.Nick Leeson disappeared from his home in Singapore's fashionable Orchard neighborhood on Thursday, as the trading irregularities became known. He was last known to be in Kuala Lumpur, the Malaysian capital, where he checked out of a hotel on Friday.

Investigators from Singapore's commercial crimes department spent 40 minutes searching Leeson's condominium Tuesday, witnesses said.

No criminal charges have been brought against Leeson, and Singapore officials would not say whether a warrant had been issued for his arrest.

But even as authorities began piecing together details of the trades Leeson made on the future price of the Tokyo stock market, his motive remained a mystery.

As in recent trading scandals in Orange County, Calif., and at the Wall Street brokerage firm Kidder Peabody & Co., a single person with the power to make huge, risky trades is being blamed for big losses.

Kidder Peabody was taken over by a rival after a crisis erupted over accusations that star trader Joseph Jett created $350 million in phony profits.

Leeson emerged as the key player in this latest financial drama. The product of public housing projects in the London suburbs, he rose to ruin the bank that counts Queen Elizabeth II among its clients.

News that Barings had gone bust jolted financial markets Monday, though the damage seemed limited and most stock exchanges recovered from their early lows.

Wall Street was the exception, showing little response before slipping in late trading on rumors that Barings' losses could exceed the 625 million pounds, or $1 billion, already acknowledged by regulators.

Prices drifted 8.4 points lower on London Stock Exchange Tuesday, but prices in Japan and other Asian stock markets rebounded somewhat.

Leeson may have simply been motivated by greed. Traders said he could expect a few million dollars in bonuses if he had a good year, far more than his base salary.

There was also speculation that Leeson made a few bad bets and doubled up, hoping to avoid getting into trouble.

"Perhaps he did a little business he shouldn't have," Bank of England Governor Eddie George suggested. "Then he tried to double up and he lost some more money. So he doubled up again to try to cover his back."

The chairman of Barings, Peter Baring, suggested in an interview Tuesday with the Financial Times that Leeson may have had an accomplice.

Leeson may have been approached by someone wanting to bet against Barings and thus cash in on the futures market, then entered into a conspiracy with that person, Peter Barings said.

Leeson's plans, whatever they were, backfired when the Tokyo market fell in recent weeks.

Administrators from Ernst and Young, who took control of Barings Monday, said they were more interested in seeing what assets could be salvaged than laying the blame.

"I don't think it's right to point any fingers at the present time. We just don't know what happened," said Nigel Hamilton of Ernst and Young.