Tencent Holdings Ltd. shares were on track to fall by their most in a decade on Tuesday after a Chinese state media outlet branded online video games ¡°spiritual opium,¡± stoking concern that the sector may be next in regulators' crosshairs.

China's biggest social media and video game firm saw its stock tumble more than 10% in morning trade, wiping almost $60 billion from its market capitalization.

Shares of rival NetEase Inc. slumped as much as 15.7%, while those of game developer XD Inc. and mobile gaming company GMGE Technology Group Ltd. also plunged.