Ant Group CEO Simon Hu suddenly resigned from his role citing personal reasons, the company said on Friday. The move comes just 15 months after taking the corner office at the Alibaba affiliate.

His exit marks Ant’s first managerial change since the financial technology giant scrapped its $37 billion IPO last year. He was one of the key executives in charge of managing what would have been the world’s largest initial public offering.

The change also comes days after some employees expressed frustration on social media for not being able to cash in their shares after Chinese regulators abruptly halted the company's market debut.

Ant has since been revamping its business after facing intense regulatory pressure to subject it to rules and capital requirements similar to banks.

The crackdown on Alibaba founder Jack Ma’s business empire began last fall after the billionaire blasted China’s regulatory system in a speech. Regulators moved to rein in Ant and launched an anti-trust probe into Alibaba in December.

Replacing Hu is executive chairman Eric Jing who had earlier served as CEO.

Alibaba’s U.S.-listed shares fell 4% in early trading.