15 contracts in the $150k account. Which is a fucking lot actually. 10 points of movement in the S&P500 means you make or lose $500 per contract. Even trading just 4 contracts at a time you can blow your account pretty quickly. Once you've built up a profit cushion you have more room to play but when you're starting at zero you can only lose $4500 of their money in the $150k account before they cut you off.

Sometimes the market can swing 10 points in like five minutes so if you're slinging 4 contracts around you can lose $2k that fast. I always ended up losing money in the long run. Sometimes I'd get lucky for a while but it never lasted.