This is because MSTY caps MSTR's upside. The fund does sell call spreads as a measure to allow itself to capture some gains in events of large spikes, but over the long-term, it will lag MSTR.

Short interest in Defiance Daily Target 2x Long MSTR ETF (NASDAQ:MSTX) decreased during the last reporting period, falling from 9.59M to 8.53M. This put -% of the company's publicly available ...