This excerpt taken from the NDAQ 8-K filed Feb 20, 2008.
2. Tender offertreasury shares
In the Exchanges Offer to Purchase (Offering) dated September 22, 2005 that expired on October 26, 2005, the Exchange offered to purchase for cash up to 16,700 shares of its Class A Common Stock at a price per share of $900. The Offering was approved by the Board of Governors on August 12, 2005. As a result of this Offering, the Exchange purchased 3,600 shares of Class A Common Stock for $3,240,000.