Bernie Madoff was an American financier and former chairman of the NASDAQ stock exchange. He is best known for orchestrating one of the largest Ponzi schemes in history, defrauding thousands of investors out of billions of dollars over several decades. In December 2008, Madoff was arrested and later sentenced to 150 years in prison. His scheme collapsed during the financial crisis, revealing that he had been using new investors' money to pay returns to earlier investors, rather than generating legitimate profits. The fallout from his actions led to significant changes in financial regulations.