Simpson Thacher & Bartlett Hong Kong partner Leiming Chen is leaving to join longtime client Alibaba Holdings Ltd.’s affiliate company Ant Financial Services Group as general counsel.

Chen will be based in Hong Kong and lead a team of 50 lawyers and compliance specialists. He reports directly to Ant Financial president Eric Jing. His appointment is an important step in Ant’s global financial services business, said Ant Financial chief executive Lucy Peng in a statement.