Hi, I traded many futures contracts for 6 years but for the first time I tried to short IXM. And this message popped: I understand that this specific regulation is to protect US from foreigners investors evading withholding tax. And I am indeed not based in the US. But: 1) It doesn't apply to broad based index: ES, NQ, any sector index except this specific one. Is it because the dividend yield for financials is usually higher than for other sectors therefore reaching a level that triggers an interdiction to trade? 2) I want to short IXM so I shouldn't be concerned by this withholding tax anti-avoidance law. 3) 871 (m) doesn't prevent traders to trade those contracts. So why shouldn't we be asked to pay withholding tax on the dividend part of the futures price instead of triggering an interdiction to trade? Of course I asked IB about it. But while I enjoy this broker, answering customer's question is not their strong point! May be some of you are aware of this regulation and/or experience same issue?