Griffin isn't retreating from AI, but he had good reasons to take some profits and rebalance his bets on the trend.

Ken Griffin is not your typical Wall Street billionaire. As the founder and CEO of Citadel , he leads one of the most sophisticated and consistently profitable hedge funds in history. He has more than earned his reputation for being a rare blend of macro strategist and quantitative mastermind.

Citadel's second-quarter 13F form, which was filed in August, revealed a pair of notable moves: The hedge fund trimmed its position in data mining specialist Palantir Technologies ( PLTR -5.39% ) by 48% -- selling roughly 640,000 shares. That left Citadel with a stake that's today worth about $130 million. At the same time, the firm boosted its position in semiconductor p

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