An "alternative trading system" is defined by the
Securities and Exchange Commission (SEC) as any system that: constitutes, maintains, or provides a market place or facilitates for bringing together purchasers and sellers of securities or otherwise performing with respect to securities the functions commonly performed by a stock exchange under Exchange Act Rule 3b-16; and does not set rules governing the conduct or subscribers or discipline subscribers other than by exclusion from trading. Such a system would consequently be required to register as an exchange or be operated by a national securities association and refrain from using the word "exchange", stock market, or similar term in it's name.