This one trader secretly controlled $70 BILLION in positions…

25 May 2026 · 1 min

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In this narrated account, Dan Novaes recounts the 2008 scandal at Société Générale where trader Jérôme Kerviel, a back‑office employee, exploited his intimate knowledge of the bank’s trade‑verification processes to build hidden, unauthorized positions that at their peak exceeded $70 billion—more than the bank’s market value. By fabricating offsetting fake trades, Kerviel concealed the real exposure for months. When market conditions turned in early 2008, the hidden bets generated massive losses. The bank was forced to unwind the positions rapidly, incurring a $5 billion loss. Kerviel was arrested and convicted, and the episode highlighted a systemic vulnerability: a single insider who fully understood internal controls could bypass them, revealing that the failure was not a broken system but an over‑reliance on procedural checks without safeguards against insider exploitation.

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In 2008, one trader lost $5 billion and almost brought down one of the oldest banks in the world. His name was Jérôme Kerviel. The bank was Société Générale. Kerviel wasn't a senior executive. He wasn't even supposed to take big risks. But he knew the system. He had worked in the bank's back office. He understood how trades were checked and how to hide them. So he started making unauthorized bets, massive ones. At one point, his positions were worth over $70 billion. That's more than the entire bank's value. But no one noticed, because he created fake trades to cover the real ones. For months, it worked. Until the market turned. Losses started piling up. Fast! The bank discovered everything in January 2008. Panic! They had to unwind his positions immediately. That's when the real damage happened. Selling everything at once, during a falling market. Total loss: $5 billion. All from one employee. Kerviel was later arrested and convicted. But the bigger shock was this: The system didn't fail because it was broken. It failed because one person understood it too well and knew exactly where no one was looking.