The National Association of Securities Dealers agreed to sell the American Stock Exchange to GTCR Golder Rauner, a Chicago-based private equity firm, in a $110 million deal, according to a published report.

The Wall Street Journal reported that the NASD signed a term sheet to sell the Amex to the firm. Although GTCR will pay $110 million to buy the exchange, the NASD will reinvest the money in the Amex, using a portion of it to meet pre-existing investment obligations and leaving the remainder of the cash on the Amex's balance sheet.

As a result, the NASD won't keep any proceeds of the sale, the report indicated. The NASD acquired the Amex in 1998. As part of the sale, the NASD will put some of the $110 million toward technological upgrades.

The deal requires several approvals, including the NASD's board of governors, the Amex members and the Securities and Exchange Commission, which means the completion of the deal might not happen for months, the Journal reported.

The agreement, reached Friday, came after nearly a year of talks between the NASD and GTCR, which brought up the idea of purchasing the Amex last summer, according to the report.