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. Oracle this year paid $1.9 billion for HR speicalist Taleo Software of Dublin, Calif., not long after arch-rival SAP (NYSE: SAP) acquired SuccessFactors of San Mateo, Calif., for $3.4 billion.

Those deals, as well as IBM's bid for Kenexa, were for substantial premiums, so as to guard against third-party bids. IBM offered more than 40 percent more for Kenexa that it's pre-announcement valuation.

Workday's Duffield, 71, used the money tfrom PeopleSoft 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. The two senior executives together own 72.4 percent of the company. Unlike Facebook (Nasdaq: FB), the No. 1 social media company, insiders don't intend to sell any of their shares in the IPO.

Venture capital firms Greylock Partners and New Enterprise Associates, both venerable technology investors, respectively own 11 and 10.1 percent interests.

Like HR rival Salesforce.com (NYSE: CRM) of San Francisco, Workday delivers all its software over the cloud.

It's not profitable yet, having posted cumulatve losses of $330 milion. For the first half of 2012, Workday's net loss rose to $46.9 million from $36.3 million a year earlier but revenue more than doubled to $119.5 million.

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

Shares of Oracle, Jive Software, Salesforce.com and regional HR rival Ultimate Software (Nasdaq: ULTI), of Weston, Fla., all rose in Friday trading.

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