Worldcom and Enron both engaged in accounting fraud in the late 1990s and early 2000s. Worldcom fraudulently reported $3.8 billion in line costs as capital expenditures instead of operating expenses. An internal audit uncovered the fraud, and Worldcom later filed for the largest bankruptcy in US history at that time. Enron used accounting loopholes and off-balance sheet entities to hide billions in debt and losses. When its stock price declined, Enron's true financial situation was revealed and it filed for bankruptcy in 2001. In response, Congress passed the Sarbanes-Oxley Act to increase accounting oversight and impose harsher penalties for corporate and accounting fraud.