Attention investors: prepare for Bitcoin's potential impact on the US stock market, advises Thomas Peterffy, chairman of Interactive Brokers. In a recent interview, Peterffy highlighted concerns over excessive leverage and Bitcoin's role in potential market volatility. The surge in margin-based risk investment in Bitcoin, facilitated by low futures fees on platforms like CME, has raised alarms. Peterffy emphasizes the severe consequences a 30-50% Bitcoin crash could trigger, including widespread bankruptcies and the potential inability of clearing organizations to cope. He advises limiting Bitcoin investments to a maximum of 10%, a prudent measure to mitigate potential financial risks. Peterffy's insights underscore the need for investors to exercise caution in navigating the dynamics between Bitcoin and traditional markets.