Bernard L. Madoff, a legend among Wall Street traders, was arrested on Thursday morning by federal agents and charged with criminal securities fraud stemming from his company’s money management business.

The arrest and criminal complaint were confirmed just before 6 p.m. Thursday by Lev L. Dassin, the acting U.S. attorney in Manhattan, and Mark Mershon, the assistant director of the Federal Bureau of Investigation.

According to the complaint, Mr. Madoff advised colleagues at the firm on Wednesday that his investment advisory business was “all just one big lie” that was “basically, a giant Ponzi scheme” that, by his estimate, had lost $50 billion over many years.