QuickLinks -- Click here to rapidly navigate through this document

UNITED STATES
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: August 8, 2003
(Date of earliest event reported)


TRANSACTION SYSTEMS ARCHITECTS, INC.
(Exact name of registrant as specified in its charter)

Delaware   0-25346   47-0772104
(State or other jurisdiction
of incorporation)
  (Commission File Number)   (I.R.S. Employer
Identification No.)

224 South 108th Avenue,
Omaha, Nebraska 68154
(Address of principal executive offices, including zip code)

(402) 334-5101
(Registrant's telephone number, including area code)





Item 5.    Other Events and Regulation FD Disclosure.

        On August 8, 2003, Transaction Systems Architects, Inc. ("TSA") issued a press release announcing that TSA has been informed that the Securities and Exchange Commission has issued a formal order of private investigation with respect to TSA's restatement of its prior period financial statements. TSA had previously announced that it has been in contact with the Securities and Exchange Commission in connection with the restatement. TSA has met with representatives of the Securities and Exchange Commission Enforcement Division and responded to questions, and subsequently provided additional written information, regarding the restatement of prior period financial statements. TSA will continue to cooperate fully with the Securities and Exchange Commission. A copy of this press release is attached hereto as Exhibit 99.1.


Item 7.    Financial Statements and Exhibits.


Exhibit
Number

  Description

99.1   Press Release, dated August 8, 2003.

2



SIGNATURE

        Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.


 

 

TRANSACTION SYSTEMS ARCHITECTS, INC.

Date: August 8, 2003

 

By:

 

/s/  
GREGORY D. DERKACHT      
Gregory D. Derkacht
President and Chief Executive Officer

3



EXHIBIT INDEX

Exhibit
Number

Description

99.1 Press Release dated August 8, 2003

4




QuickLinks

SIGNATURE
EXHIBIT INDEX

QuickLinks -- Click here to rapidly navigate through this document


Exhibit 99.1
News Release

TRANSACTION SYSTEMS ARCHITECTS, INC.
224 SOUTH 108 AVENUE
OMAHA, NEBRASKA 68154
402.334.5101
FAX 402.390.8077

For more information contact:
William J. Hoelting
Vice President, Investor Relations
402.390.8990

FOR IMMEDIATE RELEASE

TRANSACTION SYSTEMS ARCHITECTS, INC. ANNOUNCES
ISSUANCE OF FORMAL ORDER OF PRIVATE INVESTIGATION BY THE
SECURITIES AND EXCHANGE COMMISSION

(OMAHA, Neb.—August 8, 2003)—Transaction Systems Architects, Inc. (Nasdaq: TSAI), a leading global provider of enterprise e-payments and e-commerce software, previously announced that it has been in contact with the Securities and Exchange Commission in connection with the Company's restatement of its prior period financial statements. The Company has met with representatives of the Securities and Exchange Commission Enforcement Division and responded to questions, and subsequently provided additional written information, regarding the restatement of prior period financial statements. The Company announced today that it has been informed that the Securities and Exchange Commission has issued a formal order of private investigation as to matters relating to the restatements. The Company will continue to cooperate fully with the Securities and Exchange Commission.

About Transaction Systems Architects, Inc.

The Company's software facilitates electronic payments by providing consumers and companies access to their money. Its products are used to process transactions involving credit cards, debit cards, secure electronic commerce, mobile commerce, smart cards, secure electronic document delivery and payment, checks, high-value money transfers, bulk payment clearing and settlement, and enterprise e-infrastructure. The Company's solutions are used on more than 1,650 product systems in 72 countries on six continents.

Disclaimer

For a detailed discussion of risk factors regarding the Company, interested parties should review the Company's filings with the Securities and Exchange Commission, including the Company's Form 10-K filed on January 13, 2003, the Company's Form 10-Q filed on February 13, 2003 and the Company's Form 10-Q filed on May 15, 2003.




QuickLinks