Confusing loss on closing options spread

External question — Personal Finance Stack Exchange Author: ginister Original post: https://money.stackexchange.com/questions/127551 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. Today I closed a spread on $TSLA, specifically a 3x bull call expiring Aug 7th, 2020. The spread was composed of 2 legs as : Buy 1330 call Sell 1360 call My P&L on the trade before closing looked nice, roughly $800 or so profit as $TSLA had done very well the last couple of days, so I was happy to take this home. I settled the trade when the underlying was around $1400, so the P&L seemed reasonably accurate. When I placed the order to settle the spread with the mid price that IBKR supplied, the order was filled, but my P&L on the trade was a huge -$1400 or more! I am baffled as to how there was such a discrepancy before and after filling the order. Could somebody please advise what mistake I may have made when looking at my P&L and pricing the closing of the order? For clarity, the 3 1360 calls were settled at 171.70 and the 3 1330 calls at 177.75. Thanks for any help!