The consolidation of all national markets’ bid-ask spread quotations as reflected in the calculation and dissemination of the highest firm bid and the lowest firm offer for a security (or broadly an asset/ investment trading in an active market/ a public exchange) on a current and continuous basis. The national “consolidated” best bid and offer (NBBO) are considered to be firm, and market makers or specialists are required to execute orders at a price at least as favorable as its disseminated bid or offer up to the size of its disseminated bid or offer.