FYI, today the SPX Jan 2021 200 call and Jan 2021 5200 put strangle has been trading for around 4995. People have often asked how to get interest on the money in their trading account. So basically you are getting $500 in interest on a $499,500 investment over about a month and a half holding period. Not sure how margin would work in a Reg T account, but for a PM account this uses practically no margin. Note the inverse would be true as well, if you are paying high interest charges for a debit balance, you could sell this strangle.