証拠金要件の増加？

Could also be that your broker is just tightening up their own internal risk management. While volatility plays a role, sometimes they're more aggressive than others in adjusting requirements.

Definitely seeing it. My broker sent out a notice about margin increases on several equity index futures last week, specifically citing market volatility. Seems pretty widespread.

I've seen the same thing, especially on energy contracts. It seems like the brokers are hedging their own risk against the current market swings, which makes sense from their perspective.

I've seen the same thing on a couple of my equity options positions, not futures specifically, but the pattern seems consistent. Definitely makes sense that volatility would be a factor.

I've seen similar movements, particularly in contracts that have had significant price swings. It seems like the clearinghouses are adjusting for the higher market risks, which makes sense given the current environment.