815 ILCS 5/2.28
"Securities exchange" means any organization, association, or group of persons, incorporated or unincorporated, located within this State that constitutes, maintains, or provides a marketplace, facilities, or electronic communications equipment for bringing together purchasers and sellers of securities or for otherwise performing with respect to securities the functions commonly performed by a stock exchange as that term is generally understood. The term includes the marketplace, facilities, and electronic communications equipment used by such an exchange. "Securities exchange" does not include any exchange, stock market operated by a national securities association registered under Section 15A of the Federal 1934 Act, automated quotation system or board of trade whose principal place of business is located in any state other than this State, or any exchange, automated quotation system, or board of trade registered under the Federal 1934 Act or designated as a contract market under the Federal 1974 Act or any affiliate thereof, or any dealer registered under this Act, or any broker-dealer registered under any federal securities Act, or any broker-dealer who is a member of the body corporate known as the Securities Investor Protection Corporation established pursuant to the Act of Congress of the United States known as the Securities Investor Protection Act of 1970, as amended, or a member of an association of dealers or broker-dealers registered as a national securities association pursuant to Section 15A of the Federal 1934 Act, or any exchange, automated quotation system, or board of trade set forth in subsection G of Section 3 of this Act, or any other exchange, automated quotation system, or board of trade that the Secretary of State, by rule or regulation, deems to have substantially equivalent standards for listing or designation as required by any such exchange, automated quotation system, or board of trade.
815 ILCS 5/2.28