In bad times, I noticed several places increase the minimum margin requirement. I am exploring a buy-and-hold strategy, but it depends on not being forced out. FINRA/SEC margin requirements didn't appear to change last March, but several brokers / exchanges did. For instance, I believe the ES contracts required 60% margin to hold a long position open. What I am looking for a is day by day total margin requirement, broken down by instrument (ES, SPX, or SPY) and broker/exchange (e.g. IB/CME).