Spread Order

A spread order is a single instruction to a broker to buy one option and sell another option at the same time, as one linked transaction rather than two separate trades. The two legs are usually related — for example, the same underlying stock but different strike prices or different expiration dates — and the trader is buying and selling simultaneously because it's the relationship between the two prices, not the price of either option alone, that matters to the strategy.

The reason spread orders exist as a distinct order type is execution risk. If you tried to buy one option and then sell the other as two separate market orders, the price of the second leg could move against you in the seconds between the two fills, leaving you with a worse combined price than you planned, or even stuck holding only one leg. A spread order tells the broker or exchange to fill both legs together, often at a net price you specify (for instance, "pay no more than $1.20 net" for the combination), so you either get the whole package close to that price or nothing happens.

The nuance that trips people up is that a spread order is not itself a single option contract — it's a routing instruction covering multiple contracts, and how it behaves depends on the order type attached to it. It can be entered as a limit order (fill only at a specified net price or better), as a "not held" order (giving the broker discretion on timing to try to get a better fill), or with explicit trader discretion. What it generally cannot be is a stop order, because a stop is triggered by a single price crossing a level, and a spread's value is a net of two prices, which doesn't map cleanly onto that trigger mechanism.

Beginners sometimes confuse "spread order" (the mechanics of how the trade is submitted and filled) with "spread strategy" (the reason for putting on two legs, such as a vertical spread to limit risk and cost versus a single option purchase). The order type is just the plumbing; the strategy is the intent behind it.