SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K Current Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): December 10, 1997 Pegasystems Inc. --------------------------------------------------- (Exact Name of Registrant as Specified in Charter) Massachusetts 1-11859 04-2787865 ------------- ------- ---------- (State or Other Jurisdiction (Commission File (IRS Employer of Incorporation) Number) Identification Number) 101 Main Street, Cambridge, MA 02142 ------------------------------ ----- (Address of Principal Executive Offices) (Zip Code) Registrant's telephone number, including area code: (617) 374-9600 Item 4. Changes in Registrant's Certifying Accountant. On December 10, 1997, Pegasystems Inc. (the "Registrant") engaged Arthur Andersen LLP as the Registrant's independent public accountants. SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has caused this report to be signed on behalf of the undersigned thereunto duly authorized. Date: December 15, 1997 PEGASYSTEMS INC. By: /s/ Ira Vishner ------------------------------ Ira Vishner Vice President, Corporate Services, Treasurer, Chief Financial Officer