A mid-price order tries to fill at the midpoint of the bid-ask spread rather than crossing it — saving you roughly half the spread on every trade when it works. On options, where the spread is a major cost, that adds up.

How it works

Instead of buying at the ask, you place a limit at the mid (between bid and ask). If a counterparty meets you there, you fill at a better price than crossing the spread. Market makers often will fill at or near the mid on liquid options, because they still profit — so working the mid is a real, repeatable saving.

The tradeoff

A mid order may not fill if no one meets your price, or may fill slower — a problem if the market’s moving and you need in/out now. So it’s best when you have a moment to work the order, and less ideal when speed is critical (use a marketable limit then). Over many scalps, the spread saved by working the mid is significant.

Crossing the spread is the convenience tax; the mid order is how you stop paying full price on every fill — if you’re willing to wait a beat.

The takeaway

Mid-price orders save the spread — a big deal for frequent scalpers — at the cost of fill certainty. Trade liquid strikes where the mid is achievable. In scalping the spread you save goes straight to your bottom line (the real cost of scalping).