BlueCrest Capital Management, one of Europe's largest hedge fund firms, laid off several stock traders in the US Thursday and began liquidating their investments, according to people familiar with the matter, not long after it aggressively expanded into equities.

Four of 18 US portfolio managers at BlueCrest's US stock hedge fund were laid off Thursday, along with their analysts, one of the people said. Jonathan Larkin, the firm's head of US equities and a former executive at Millennium Management, resigned, the people said.