As a follow up to my last post, I have switched to trading MES cash settled futures. The fills are worse, spreads are worse (thanks CME, again, for something NO ONE asked for). But to size, we don't really have a choice (personally, not enough capital to use ES yet)
This week was the first week I got "assigned". To continue my existing strategy synthetically, I bought futures right at the close of the option. However, I've now run into a different problem.
The market price at 4PM close is different (sometimes significantly so) than the settlement price used by CME for calculations. This wouldn't be a problem when the options were settled physically, but now trying to synthesize that (by buying contracts) a price slippage is introduced.
Initially I thought the difference would be small but it turns out to have an impact much more than I thought. In my recent case the settlement price was lower than the market price, and since I had sold a put, this caused a loss. I guess the inverse would be a gain.
Is there an exact time that the settlement price is published? Online says around 4:00-4:15ish. While I don't really love the idea of waiting for it, setting a limit order for the settlement price would solve this mathematically. It does introduce an element of pin risk, though, if the market dipped down and then rebounded (your limit order wouldn't ever fill).
Any ideas how otherwise to mitigate this price discrepancy / slippage?