If you want a leveraged position in the S&P 500 (either long or short), you can buy/sell S&P 500 futures with an implied financing rate that is approximately th

If you want a leveraged position in the S&P 500 (either long or short), you can buy/sell S&P 500 futures with an implied financing rate that is approximately the risk-free rate. That's better than using margin. If you did use margin, Interactive Brokers offers lower margin rates than most retail brokers.