??41.15 Exclusion from definition of narrow-based security index for indexes composed of debt securities.(a) An index is not a narrow-based security index if:(1)(i) Each of the securities of an issuer included in the index is a security, as defined in section 2(a)(1) of the Securities Act of 1933 and section 3 (a)(10) of the Securities Exchange Act of 1934 and the respective rules promulgated ther