A star trader at Ken Griffin’s Citadel hedge fund, whose team made billions trading natural gas during Russia’s invasion of Ukraine, is stepping down amid the most volatile period for the asset class in years. Chris Foster, who has traded natural gas in Europe at Citadel for nearly two decades, is stepping down from the role. Foster built the business in Europe into one of the hedge fund’s most important profit centres and led the team there for most of his career.

Oil and natural gas prices have surged since the start of the Iran war early in 2026, creating a tumultuous landscape for traders navigating frequent ups and downs in hostilities between the US and Iran. This week, renewed conflict hit the energy sector again, and European natural gas prices hit their highest levels in three years.

Foster will continue as a senior adviser to Sebastian Barrack, head of Citadel’s commodities business. Since last year, the European natural gas team has been led by Stephen Carter and Adam Frame, whom Foster hired. Barrack praised Foster’s leadership in building the industry-leading team.

Citadel’s commodity business made record hauls around Russia’s 2022 invasion, with an estimated $8bn that year, largely from European gas trades. Foster’s team made about $2bn alone. In 2023, Griffin estimated the unit contributed $30bn over the years. However, returns have been muted in 2025 and 2026. Citadel’s success inspired rivals, and it acquired Paloma Natural Gas in March 2025, now Apex Natural Gas.