If you talk to a French trader, they will inform you that mathematics graduates from École Polytechnique are France’s finest mathematicians. Mathematics graduates from École Polytechnique who also have a DEA El Karoui are even better.
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Citi had someone who combined these two achievements. Now Marouen Ben Othman has gone to Brevan Howard instead. As of this month, he is a senior portfolio manager at the British hedge fund, based in New York City.
Ben Othman was Citi’s head of index flow trading, a desk that trades derivatives based on equity indices. He joined the bank from JPMorgan in 2022 and previously worked for Credit Suisse.
Brevan Howard declined to comment on Ben Othman’s arrival and Citi didn’t respond to a request to comment on his departure.
Citi’s New York equity derivatives team has a history of losing people to hedge funds. Seok Yoon Jong, a former head of Americas flow volatility trading, left for Brevan in 2021 but recently moved again – to Millennium. Etienne Lussiez, a former head of index flow derivatives trading at Citi, left for Citadel Securities in 2022, and has been on an non-compete since December 2025.
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