A pegged order that is indexed to the national best bid and offer (NBBO) on the same side of the market.More specifically, buy orders are pegged to the bid (with or without an offset), while sell orders are pegged to the offer (with or without an offset). The NBBO, as a quote, provides information as to the highest bid price and lowest ask (offered) price in a given security, sourced from among all available exchanges or venues.

The exchange system will automatically adjust the price of the ordered entered and posted to the order book, in accordance with the changes in the national best bid (NBB) for buy orders up to the order’s limit price, if any (in accordance with the changes in the national best offer (NBO) for sell orders down to the order’s limit price, if any).