A system and method for operating an on-demand auction for a Financial Instrument are provided in which a request is made for a Trading Center to conduct an on-demand auction for a Financial Instrument. If requirements are met, the Trading Center transitions from an Open Trading State (OTS) to a SNAP Auction State (SAS), excludes from the auction any order which explicitly requests exclusion, includes in the auction any remaining Resting Orders, includes in the auction certain new orders which arrive before the auction ends, activates and includes currently dormant orders, takes a snapshot of displayed buying/selling interest and attempts to include in the auction any available buying/selling interest in other Trading Centers which must be satisfied, computes the auction price, sends external Satisfaction Orders, attempts to match all responses to Satisfaction Orders and all internal orders included in the auction, and transitions back from the SAS to the OTS.
