Bernard L. Madoff pleaded guilty Thursday to all the charges against him in a vast Ponzi scheme that bilked investors out of billions of dollars.

Standing before Judge Denny Chin in United States District Court in Manhattan, Mr. Madoff was sworn in and reminded that he was under oath. Noting that he had waived indictment, Judge Chin asked, “How do you now plead,” guilty or not guilty?

“Guilty,” Mr. Madoff responded.

His immediate fate remains in the balance. The judge is expected to rule later Thursday on whether Mr. Madoff will remain free on bail and return to his apartment on Manhattan’s Upper East Side, or be immediately jailed as he awaits sentencing.

The 11 counts of fraud, money laundering, perjury and theft to which he pleaded guilty carry maximum terms totaling 150 years.

Dressed in a gray suit, Mr. Madoff, 70, appeared in a courtroom packed with journalists, lawyers and some of his victims. Flanked by his lawyers, he stood up and began to answer questions from Judge Chin about whether he understood the ramifications of his guilty plea, whether he was satisfied with his legal representation and whether he was competent to enter the guilty plea.

At first, Mr. Madoff’s voice was barely audible as he acknowledged the litany of crimes.

“Try to keep your voice up so that I can hear you, please,” Judge Chin said.

The court session marks the first time since his arrest by federal agents on Dec. 11 that Mr. Madoff has spoken publicly about how he ran what was perhaps the largest fraud in Wall Street history, a global scheme that ensnared hedge funds, nonprofit groups and celebrities, and devastated the life savings of thousands of people.

After his plea, Mr. Madoff was to answer questions about how he sustained a 20-year fraud whose collapse erased as much as $65 billion that his customers thought they had in their accounts. Judge Chin was then to announce whether the plea was accepted.

Some of Mr. Madoff’s victims are also expected to speak on whether the judge should accept Mr. Madoff’s guilty plea, and whether his $10 million bail should be revoked.

But it remains unclear where the billions of dollars that his victims lost has gone, and whether those victims will ever see any meaningful restitution. Prosecutors have said the government is seeking $170 billion in forfeited assets from Mr. Madoff, apparently representing all the money that ran through Madoff accounts traceable to the crimes.

A court-appointed trustee liquidating Mr. Madoff’s business has so far only been able to identify about $1 billion in assets to satisfy claims.

This week, the government said Mr. Madoff had 4,800 client accounts at the end of November supposedly containing $64.8 billion in customer savings. But the government said Mr. Madoff’s business “held only a small fraction of that balance.”

As Mr. Madoff arrived at the courthouse early Thursday morning, helicopters buzzed overhead and television news trucks lined the street. The day’s events marked a coda in the saga of a man whose name has become shorthand for an entire era of greed and deceit on Wall Street.

With the promise of steady, unwavering returns, Bernard L. Madoff Investment Securities enticed thousands of investors including boldface names like Senator Frank Lautenberg of New Jersey, the Hall of Fame pitcher Sandy Koufax and a charity run by the Nobel Peace Prize laureate Elie Wiesel.

This week, the government offered more details on how Mr. Madoff ran the fraud that had financed his lush lifestyle of a beachfront mansion in the Hamptons, an estate near the French Riviera and yachts in New York, Florida and the Mediterranean.

Prosecutors said that Mr. Madoff concocted an elaborate charade to make it seem like he was running a legitimate investment business when, in reality, “no such business was actually being conducted.” He hired employees with little training or experience and directed them to generate false monthly account statements.

He shuttled millions between banks in New York and London to make it seem as if he was “conducting securities transactions in Europe on behalf of investors when, in fact, he was not conducting such transactions,” prosecutors said. And they said he repeatedly lied to regulators from the Securities and Exchange Commission to cover up his scheme.