China’s securities regulator has fined three of the country’s largest investment banks for facilitating bearish bets on the stock market by a unit of US-based Citadel Securities during the Chinese market rout of late 2015. 

Citic Securities, China’s largest brokerage by revenue, was fined Rmb308m ($45m) and required to forfeit an additional Rmb62m in profits earned from securities lending and margin financing for a Shanghai account operated by Citadel Securities, a market-making arm separate from the fund founded by Ken Griffin , according to an exchange filing. Two executives were also fined.

In summer 2015, as China’s stock market was falling sharply after a strong run the previous year, regulators targeted “malicious short sellers” whose trading practices they believed crossed the line into market manipulation.