The term price improvement refers to the process of obtaining a lower than offer price when buying a security or a higher than bid price when selling a security. Price improvement is one of the possible outcomes from a broker's duty of best execution.
The duty of best execution is a requirement under the jurisdiction of the Securities and Exchange Commission (SEC). This requirement mandates a broker to seek out the most favorable terms of execution reasonably available to their clients, including securing the best possible price. Price improvement is measured against the National Best Bid and Offer (NBBO), which is a consolidated quote of bid and ask prices compiled from all visible quotes. Price improvement can occur in two ways:
An investor would like to sell 500 shares of Company ABC's common stock. When the investor contacts their broker to place the order, the NBBO bid price was $100.00. After executing the order, the broker informs the investor they were able to sell the securities for $100.50 per share. The price improvement of $0.50 per share results in the investor realizing an additional profit of $0.50 x 500, or $250.00.