Unpriced order auction and routing

A A method comprising:

• scheduling, by a computer system comprising at least one processor and non-transitory memory storing executable program code, a single-price auction for shares of an issue to occur intra-day at a scheduled auction time concurrently with and separately from a continuous matching process executed by a continuous matching engine of the computer system;
• receiving, by an order and execution interface of the computer system, a plurality of electronic orders comprising one or more limit orders that include a specified price and one or more unpriced orders that do not include a specified price;
• automatically directing, by the order and execution interface, the one or more limit orders to the continuous matching engine and the one or more unpriced orders to an unpriced order auction engine of the computer system;
• continuously updating and disseminating in real-time, by the unpriced order auction engine, until the scheduled auction time, an auction imbalance volume comprising a difference between an aggregate volume of the one or more unpriced orders to buy shares and an aggregate volume of the one or more unpriced orders to sell shares;
• responsive to disseminating the auction imbalance volume, receiving, by the order and execution interface, one or more of the following responses until the scheduled auction time:
• one or more new unpriced orders, one or more cancellations of previously received unpriced orders, and one or more instructions requesting modifications to previously received unpriced orders;
• updating, by the unpriced order auction engine, the auction imbalance volume based on the received one or more responses until the scheduled auction time;
• and
• executing, by the unpriced order auction engine, the single-price auction at the scheduled auction time, wherein the continuous matching process is not interrupted by the single price auction at any time before or during the single-price auction, by:
• determining, by the unpriced order auction engine, a single auction price comprising a midpoint of a national best bid and offer (NBBO) quote;
• and
• executing, by the unpriced order auction engine, at the determined single auction price, one or more trades of the one or more unpriced orders to buy shares matched with the one or more unpriced orders to sells shares.