INDENTURE

Exhibit 4.1

EXECUTION COPY

SPSS INC.

AND

WILMINGTON TRUST FSB
as Successor Trustee

FIRST SUPPLEMENTAL INDENTURE

Dated as of October 2, 2009

to

INDENTURE

Dated as of March 19, 2007

2.50% Convertible Subordinated Notes due 2012

      FIRST SUPPLEMENTAL INDENTURE , dated as of October 2, 2009 (the “First Supplemental Indenture”), between SPSS INC., a Delaware corporation (hereinafter called the “Company”), and WILMINGTON TRUST FSB, as successor trustee (hereinafter called the “Trustee”).

RECITALS

      WHEREAS , the Company executed and delivered to the LaSalle Bank National Association, as predecessor trustee to the Trustee, that certain Indenture, dated as of March 19, 2007 (the “Indenture”), pursuant to which the 2.50% Convertible Subordinated Notes of the Company (the “Notes”) were issued;

      WHEREAS , pursuant to the terms of the Indenture, the Notes are convertible into shares of common stock, par value $0.01 per share, of the Company (“Common Stock”);

      WHEREAS , pursuant to an Agreement and Plan of Merger, dated as of July 27, 2009 (the “Merger Agreement”), among the Company, International Business Machines Corporation, a New York corporation (“IBM”), and Pipestone Acquisition Corp., a Delaware corporation and a wholly owned subsidiary of IBM (“Merger Sub”), Merger Sub will merge with and into the Company (the “Merger”), with the Company as the surviving corporation and a wholly owned subsidiary of IBM, as a result of which each issued and outstanding share of Common Stock (other than shares of Common Stock held by the Company, IBM or Merger Sub) shall be converted into the right to receive $50.00 in cash, without interest and less any applicable withholding taxes (the “Merger Consideration”), and such shares of Common Stock shall no longer be outstanding and shall automatically be cancelled and cease to exist, and each holder of a certificate or evidence of shares in book-entry form that immediately prior to the effective time of the Merger represented any such shares shall cease to have any right with respect thereto, except the right to receive the Merger Consideration in accordance with the terms of the Merger Agreement;

      WHEREAS , Section 4.10 of the Indenture requires the Company to execute and deliver to the Trustee this First Supplemental Indenture in order to reflect the effect of the Merger on the holders of Common Stock; and

      WHEREAS , the consummation of the Merger shall constitute a Fundamental Change (as such term is defined in the Indenture).

      NOW, THEREFORE, in consideration of the premises, it is mutually agreed, for the equal and proportionate benefit of the respective Holders from time to time of the Notes, as follows:

ARTICLE ONE
CONCERNING THE NOTES