The U.S. Securities and Exchange Commission (SEC) is investigating allegations of insider trading involving Futu Holdings and UP Fintech (Tiger Brokers), following claims by market maker Susquehanna. Unknown traders reportedly purchased significant amounts of U.S. stock options linked to these firms before Chinese regulators announced a crackdown on May 22, turning $12 million into profits exceeding $100 million. Susquehanna, which incurred losses over $70 million, prompted a U.S. court to freeze assets of suspected accounts on platforms including Interactive Brokers, Futu, and UP Fintech, and issued subpoenas to reveal the identities of the account holders. This investigation follows a substantial fine of approximately 1.85 billion yuan imposed by Chinese regulators on Futu for providing unlicensed cross-border securities trading services to mainland investors. The regulatory action led to a sharp decline in Futu's stock price, significantly impacting the net worth of its founder, Leaf Li, by about $1.7 billion in a single day.