The Oracle-PeopleSoft merger battle has claimed another victim. PeopleSoft Inc. disclosed in a regulatory filing Tuesday that chairman and CEO David Duffield resigned from the company last week, less than three months after taking the job.

PeopleSoft agreed to a $10.3 billion acquisition by Oracle earlier this month after a bitter 18-month takeover fight that led to the ouster of PeopleSoft's previous CEO, Craig Conway.

In a filing with the Securities and Exchange Commission, PeopleSoft stated that Duffield, who founded the company in 1987, resigned his positions of director, board chairman, and CEO on Dec. 21. PeopleSoft's acquisition by Oracle, which consolidates two of the largest players in the business software market, is expected to close in early January. Sources close to PeopleSoft don't expect the company to appoint an interim CEO.

A PeopleSoft spokesman had no comment on the resignation. An Oracle spokeswoman also declined comment but said the company will disclose more information about the acquisition of PeopleSoft at Oracle's conference for financial analysts Jan. 26 in New York.

PeopleSoft's board finally agreed to sell the company to Oracle this month after a year and a half of resisting lower offers. Following the board's vote, Duffield sent an E-mail to PeopleSoft staffers apologizing for not keeping the company independent. During the takeover battle, Duffield had threatened to sue Oracle CEO Larry Ellison for defamation over information Oracle released about Duffield's stock sales.

Duffield, who was PeopleSoft's chairman since its founding and who served as CEO from 1987 to 1999, returned as chief executive in October after the company's board fired Conway--himself a former Oracle executive--over his handling of Oracle's hostile bid, launched in June 2003.

Shares of PeopleSoft (Nasdaq-PSFT) closed down 4 cents Tuesday at $26.40, while shares of Oracle (Nasdaq-ORCL) climbed 19 cents to close at $13.84.