There is no disseminated spread market that provides a benchmark price (such as the national best bid or offer [NBBO] for individual option series) for spread orders. Therefore, liquidity providers cannot be held to a net price on a spread order and you may not receive the NBBO on each individual leg of a spread.
Spread trades are executed as a single trade and are not legged or paired as individual trades. When trading spreads, option prices on cross-markets may be misleading because the legs of the spread cannot be executed on different exchanges to get the NBBO for each leg. Both legs of the spread must be executed on the same exchange.
Spread trades are executed at the discretion of the specialists or market makers responsible for executing your orders on the exchanges. When a spread order is cancelled or filled, the specialist or market maker may be required to take manual action that may require additional reporting. Such delays in reporting fills and cancels create risks, especially in fast-moving markets. Any trade executed via the OptionsHouse spread ticket will be sent to the exchange as a spread trade and will be subject to the risks outlined above.