Hello everyone,

I’ve been trying to sell a 200-point wide SPX box spread ($20k notional) on IBKR for the April 16, 2027 expiration (~160 DTE), but haven’t been able to get a fill yet.

I selected the 7800 / 8000 strikes since they had the highest open interest. However, when I build the 4-leg combo, the displayed ask is sitting around -190.00 (which implies a ~12% annualized rate), whereas boxtrades.com suggests a fair limit price around -196.00 (~4.74%).

For those who trade SPX boxes:

1. Is the -190 quote just noise from wide bid-ask spreads on the individual legs, and should I just leave a resting limit order around -196.00 during regular trading hours?

2. Does choosing strikes closer to ATM (e.g., 5800/6000) improve fill speed compared to deep OTM strikes like 7800/8000?

Appreciate any guidance!