Pleasanton, Calif. -- Workday, a Pleasanton-based developer of web-based tools for human resources, payroll and financial management, has confidentially filed with the Securities and Exchange Commission (SEC) for its initial public offering (IPO), Reuters reported. The company reportedly filed a week ago, but so far has been able to shield details of the IPO through a newly enacted law called the JOBS Act. Citing unnamed sources, Reuters said the company plans to price this fall in what could be the largest IPO since Facebook. Workday has raised $250 million in funding since its founding in 2004 by former PeopleSoft executives Dave Duffield and Aneel Bhusr. Top backers include Greylock Partners, New Enterprise Associates, Morgan Stanley Investment Management, T. Rowe Price, Janus Capital Group and Bezos Expeditions.