John Chen, who has managed software vendor Sybase for 15 years and continued to lead the company after its 2010 acquisition by SAP, is stepping down from the job effective tomorrow.

Chen, in a statement issued Tuesday, said he was leaving to "take on a new challenge," but did not disclose additional information about his plans. In an interview with Bloomberg, Chen said he had not yet decided what his next job would be.

"After 15 years of leading Sybase, I want to take on a new challenge," Chen said. "The integration of Sybase into SAP is complete and the business is in great shape. Combining the organizations made sense and I am pleased with the direction of the mobile and database business of Sybase within SAP. The Sybase assets are contributing significantly to SAP's success and benefitting from technology such as SAP HANA as well as the global reach of the company. I leave knowing that what we built is in good hands."

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Chen, 57, became president and chief operating officer of Sybase in 1997 when the company -- then largely reliant on its flagship database product -- was struggling against Oracle and other database software competitors. Chen expanded the company's focus to include mobility and business analytics software, returning the company to growth and profitability. Chen became CEO and chairman in November 1998.

Application powerhouse SAP acquired Sybase in July 2010 for $5.8 billion. Since then Chen has continued to run Sybase as a subsidiary while SAP has leveraged the company's mobile and data management technologies.

Chen's departure is effective Oct. 31. An SAP spokesman said the company doesn't plan to maintain the Sybase president/CEO post, "now that we've successfully integrated Sybase into the SAP organization."

"John is a pioneer who contributed greatly to the enterprise mobility and database markets, and I am incredibly proud of what we have done together," said Vishal Sikka, a member of the SAP Executive Board, Technology & Innovation, in the company's statement.

"Together with John, we have expanded the Sybase business significantly since the acquisition," said a statement attributed to SAP co-CEOs Bill McDermott and Jim Hagemann Snabe. "Today we are the market leader in mobility and the fastest growing database company in the industry. We respect John's decision, we know that he will remain a friend of SAP and we wish him all the best for the future."

PUBLISHED OCT. 30, 2012

This story was updated on Oct. 30, 2012, at 12:10 p.m. PST, to add additional information from Chen's interview with Bloomberg and comments from an SAP spokesman made after press time.