striking or 1256 and inserting or 491 , and (B) by striking 1092, and 1256 and inserting 491, and 1092 . (5) Section 1091(e) is amended to read as follows: (e) Coordination with mark to market of derivatives and underlying investments For purposes of this section, the term stock or securities shall not include— (1) any derivative (as defined in section 493), or (2) any underlying investment (as defined in section 492(e)(1)) which, at the time of the sale or other disposition, is part of an investment hedging unit (as defined in section 492). . (6) (A) Section 1221(a)(6) is amended to read as follows: (6) any— (A) derivative (as defined in section 493), or (B) any underlying investment (as defined in section 492(e)(1)) which is part of an investment hedging unit (as defined in section 492), . (B) Section 1221(b) is amended by striking paragraph (1). (7) Section 4975(f)(11)(D) is amended by striking clauses (i) and (ii) and inserting the following: (i) Security The term security means any security described in section 475(c)(2) (without regard to subparagraph (D)(iii) thereof) and any derivative with respect to such a security (within the meaning of section 493). (ii) Commodity The term commodity means any commodity described in section 475(e)(2) (without regard to subparagraph (B)(iii) thereof) and any derivative with respect to such a commodity (within the meaning of section 493). . (8) The table of parts for subchapter E of chapter 1 is amended by adding at the end the following new item: Part IV. Tax treatment of derivatives and similar contracts . 5. Effective dates (a) In general Except as provided in this Act— (1) the amendments made by section 2 shall apply to taxable events occurring after the 90-day period beginning with the date of the enactment of this Act, in taxable years ending after the last day of such period, and (2) the amendments made by sections 3 and 4 shall apply to derivatives and underlying investments held after the last day of such period. (b) Identification requirements If, as of the