The former chief executive of Refco Inc., one of the world’s biggest commodities brokerages, cried as he pleaded guilty Friday to conspiracy and fraud charges.

Phillip R. Bennett, 59, the company’s former chairman and chief executive officer, pleaded guilty before U.S. District Judge Naomi Reice Buchwald to 20 counts of conspiracy to commit securities fraud, wire fraud, bank fraud, money laundering and making false filings to the SEC.