I heard in the Traders Laboratory forums that the EUREX used to activate overnight margin requirements for the DAX while the contract was still open, at about 4:30 local time? Is this true? Do they still do this? I'm particularly curious about the euro stoxx contract.... It would be disastrous to hold a contract during the market thinking that intra day margins apply but actually the overnight margins are in place...lol! Cheers.
Yes, this could happen. Intraday margins are a decision of the broker and I'm not sure who determines the time of switch to overnight margins but anyway you have to be aware of this time and reduce your positions accordingly. Don't know about other brokers but Interactive Brokers for the time being have suspended intraday margins, so you don't have to worry about this just now. I guess VIX will have to drop below 30 before they will reinstate them. The exchanges have raised their margin requirements due to the current volatility. For Eurex Bonds margins have about tripled - compared to the old intraday margins.