The controller of prominent Chinese gaming company Kingnet, Wang Yue, has been detained by Shanghai police on suspicion of “manipulating” stock trading, the company said in a Tuesday filing submitted to the Shenzhen Stock Exchange.

In an earlier investment risk warning, submitted in March, the company said it couldn't fully address the regulator's concerns over management personnel shifts as it failed to reach Wang at the time, who had voluntarily resigned as chair of the company’s board three days before. It is unclear whether the resignation was related to Wang’s detention.

Wang still holds 21.44% of Kingnet’s total shares.

Established in 2008, Kingnet has developed popular games in China, but is currently under profitability pressure. The company’s annual net profits shrank from 1.6 billion yuan ($236 million) in 2017 to 174 million yuan in 2018, though revenues of the game MU Miracle, which it operates in China, have surpassed $10 billion since it debuted in 2014, a company fiscal report shows.

Related: Foreign Game Approvals Good News for Tencent, NetEase