Workday, the human-resource software company started by PeopleSoft founder David Duffield, filed for a $400 million initial public offering sometime later this year.

The filing with the U.S. Securities and Exchange Commission follows Monday's announcement that International Business Machines Corp. (NYSE: IBM) would acquire rival Kenexa Corp. (Nasdaq: KNXA) of Wayne, Pa., for $1.6 billion.

Duffield's first company, PeopleSoft, was a pioneer in the sector and was taken over by Oracle (Nasdaq: ORCL), the No. 1 database developer, after a bitter battle and paying shareholders $11.1 billion.

Duffield, 71, used the money to seed Workday, of Pleasanton, Calif., and now owns 73.5 million shares as its biggest shareholder. Co-CEO Aneel Bhusri, 46, with 27.4 million shares, is the second-largest shareholder, the filing showed.

Workday said its principal underwriters are Morgan Stanley (NYSE: MS) and Goldman Sachs (NYSE: GS).