I'm trying to understand the market mechanics of futures with delivery. For sake of example, assume 0 interest rates and no cost of carry, and that I bought a futures contract on Jan 1 with Feb 1 expiry for $100, on some fictional commodity. On Feb 1 the spot price proves to be $150. I put in $20 in the margin account. So, am I correct in saying that
- my margin account will have increased by $50
- I pay $100 to the clearing house and am delivered the commodity
- I can sell the commodity in the spot market for $150, thus pocketing $150-$100 = $50 off of this transaction and the last
- I made $100 on this trade, 50 from the margin acct and 50 from the previous bullet point??
Basically to me it seems like I made 50 dollars twice, once through the margin account, and once via the spot market and futures expiry. Obviously something is wrong here. My question is:
Does the futures price moving from 100 to 150 mean I can make 50+50=100? Or is my logic wrong somewhere?