Millennium Management's "Billions-Dollar" Index Rebalancing Strategy Became a $900M Blunder

Millennium Management—the hedge fund so obsessed with risk that it fires PMs for losing 5%—tasked two of its most decorated teams with what should have been a routine play: profiting off index rebalancing. These weren't amateurs. Scheinberg and Madhvani's teams had made billions executing this trade flawlessly for years. How hard could it be? Apparently, extremely hard. In February 2025, they lost $900 million. The Wall Street Journal reported it. Bloomberg followed up. And one quantitative researcher at a rival firm tweeted out the brutal truth: "Index rebalancing looks simple. It isn't. So many things can go wrong, so much risk tolerance is needed, so much craft goes into this conceptually simple trade that very few teams can do it well." Millennium's teams, it turned out, were not in that "very few." At least one PM has already left the fund. Several more likely followed.