According to Caixin, one of the largest options market makers in the United States, Susquehanna International Group, filed a lawsuit on June 29, 2026, with the U.S. District Court for the Southern District of New York in Manhattan, alleging that hundreds of people were suspected of having obtained advance notice of China’s regulatory action on May 22 to crack down on illegal cross-border stock trading. The court filing claims that unusually large-volume buying of the penalized Tiger Brokers and Futu Holding put options led to profits of more than $100 million. According to Caixin, one possible source of the insider traders involved is from China’s securities regulatory authorities, while the other may be individuals associated with Futu or Tiger Brokers who were able to discuss enforcement actions with China’s securities regulators.