24 Table of Contents Reference Number per Item 601 of Regulation S- K Description of Exhibits Exhibit Number in this Form 10-K The instrument defining the rights of the holders of the 0.30% Notes due 2026 is Exhibit 4 to Form 8-K filed November 1, 2016, and is hereby incorporated by reference. The instruments defining the rights of the holders of the 2.500% Notes due 2022 and 3.300% Notes due 2027 are Exhibits 4.3 and 4.4 to Form 8-K filed January 26, 2017, and are hereby incorporated by reference. The instruments defining the rights of the holders of the 0.950% Notes due 2025, and 1.500% Notes due 2029 are Exhibits 4.1 and 4.2 to Form 8-K filed May 22, 2017, and are hereby incorporated by reference. The instruments defining the rights of the holders of the 0.375% Notes due 2023, the 0.875% Notes due 2025, the 1.250% Notes due 2027 and the 1.750% Notes due 2031 are Exhibits 4.1, 4.2, 4.3 and 4.4 to Form 8-K, filed January 30, 2019, and are hereby incorporated by reference. The instruments defining the rights of the holders of the Floating Rate Notes due  2021, 2.800% Notes due 2021, the 2.850% Notes due 2022. the 3.000% Notes due  2024, the 3.300% Notes due 2026, the 3.500% Notes due 2029, the 4.150% Notes  due 2039 and the 4.250% Notes due 2049 are Exhibits 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7  and 4.8 to Form 8-K, filed May 14, 2019, and are hereby incorporated by reference. The instruments defining the rights of the holders of the 0.300% Notes due 2028, the 0.650% Notes due 2032 and the 1.200% Notes due 2040 are Exhibits 4.1, 4.2 and 4.3 to Form 8-K, filed February 10, 2020, and are hereby incorporated by reference. Indenture dated as of October 1, 1993 between IBM and The Bank of New York Mellon, (as successor to The Chase Manhattan Bank (National Association)) as Trustee, is Exhibit 4.1 to Form 10-Q for the quarter ended September 30, 2017, and is hereby incorporated by reference. First Supplemental Indenture to Indenture dated as of October 1, 1993 between IBM and The Bank of New York Mellon, (as successor to The Chase Manhattan Bank (National Association)) as Trustee, dated as of December 15, 1995, is Exhibit 4.2 to Form 10-Q for the quarter ended September 30, 2017, and is hereby incorporated by reference. Description of Securities Registered under Section 12 of the Exchange Act 4.1 (9) Voting trust agreement Not applicable (10) Material contracts The IBM 2001 Long-Term Performance Plan, a compensatory plan, contained in Registration Statement No. 333-87708 on Form S-8, as such amended plan was filed as Exhibit 10.1 to Form 10-Q for the quarter ended September 30, 2007, is hereby incorporated by reference.* The IBM PWCC Acquisition Long-Term Performance Plan, a compensatory plan, contained in Registration Statement No. 333-102872 on Form S-8, as such amended plan was filed as Exhibit 10.2 to Form 10-Q for the quarter ended September 30, 2007, is hereby incorporated by reference.* The IBM 1999 Long-Term Performance Plan, a compensatory plan, contained in Registration Statement No. 333-30424 on Form S-8, as such amended plan was filed as Exhibit 10.3 to Form 10-Q for the quarter ended September 30, 2007, is hereby incorporated by reference.*