Bill Ackman, the founder of Pershing Square Capital Management, has recently expressed concerns regarding highly-leveraged exchange-traded funds (ETFs) and zero-day stock contracts, which have gained popularity among day traders. His remarks come in the wake of a challenging period for his fund, which reported a 12.9% loss in early April and a year-to-date decline of approximately 14%. Ackman has also raised questions about the viability of 3x ETFs, which have been in existence for nearly two decades. His comments reflect a broader skepticism towards technical market factors influencing recent trading trends. The market's volatility has led to speculation about Ackman's future strategies, including potential calls for regulatory changes such as a ban on short selling.