The National Association of Securities Dealers closed the sale of the American Stock Exchange to members of the exchange, Amex said today.

“As an independent institution, the Amex can better manage its opportunities and challenges, and compete more aggressively in the marketplace,” Amex chairman and CEO Salvatore Sodano said in a release.

As part of the sale, Amex will elect a new 15-member board of governors — nine independent and six from the securities industry..

“The transition to a new board will be carried out according to rules approved by the membership,” said Anthony Boglioli, Amex vice chairman.