NEW YORK (CNN/Money) - The National Association of Securities Dealers said Monday it has agreed to sell the 100-year-old American Stock Exchange to GTCR Golder Rauner LLC, a private equity firm, for $110 million.

The deal is subject to approval by the Securities and Exchange Commission, the boards of the Amex and the NASD, and the vote of the Amex membership.

"One of our key goals over the last few years has been to exit NASD's ownership of exchanges and to focus our entire organization on NASD's core mission as a regulator to promote market integrity and protect investors," NASD Chairman and CEO Robert Glabuer said in a joint statement with the Amex.

"The agreement reached with GTCR should ensure that a strengthened Amex can continue to be a vital participant in our financial markets," Amex Chairman and CEO Salvatore Sodano added.

Last week, an industry source told Reuters that a subcommittee of the NASD board gave preliminary approval to sell the exchange to GTCR, despite a recent overture from Chicago Board Options Exchange.

No layoffs are expected as a result of the deal, which is expected to be completed in the next 30 to 60 days, the source said. At the end of May, the Chicago Board proposed "a strategic combination" with Amex to win back market share from the all-electronic International Securities Exchange, the current leader in equity options.

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But the proposal from the world's largest options exchange came late in the game for the Amex, which has been on the selling block for more than two years. Amex, the No. 3 exchange, is the only domestic exchange that trades three types of securities: options, stocks, and ETFs, or exchange-traded funds.

NASD purchased the Amex in 1998, billing the merger as a way to lower fees for investors who could choose if they wanted their shares traded on the Amex, which uses a floor-based auction system, or the Nasdaq Stock Market Inc., where traders compete for orders electronically.

But amid rising competition from electronic trading venues and changing market conditions, the benefits of the deal failed to materialize. In 2000, NASD began the process of spinning off Nasdaq and later, it put the Amex on the block, saying it wanted to concentrate solely on regulation.

NASD said it will use the funds generated by the Amex sale to upgrade the exchange's infrastructure and operations.