Depends whether you’re holding it as SPY/VOO or as a mutual fund (assuming you don’t mean SPX futures, and SPX itself isn’t tradeable). IBKR has somewhat higher margin requirements than the minimums set by the OCC; I think they require 25% maintenance margin for mutual funds and 10-15% for broad-based stock indices.
Depends whether you’re holding it as SPY/VOO or as a mutual fund (assuming you don’t mean SPX futures, and SPX itself isn’t tradeable). IBKR has somewhat higher margin requirements than the minimums set by the OCC; I think they require 25% maintenance margin for mutual funds and 10-15% for broad-based stock indices.