Oracle founder Larry Ellison is stepping down as head of the company he founded, news reports announced Thursday evening. While many analysts expected he would resign the helm soon, the timing of his announcement was a suprise to more than a few.

Ellison built Oracle and its widely used database software into one of Silicon Valley's most powerful companies, fattening its portfolio with massive acquisitions and a broad range of enterprise solutions.

The 70-year-old Ellison is putting the company in the hands of Safra Catz, 52, and Mark Hurd, 57, who will serve as co-CEOs, after serving as CEO for 37 years. Ellison will continue working for Oracle full time as chief technology officer. The software and hardware engineering teams will continue to report to Ellison.

"I'm going to continue doing what I've been doing over the last several years -- they're going to continue what they've been doing over the last several years," said Ellison. "Mark and Safra have done a spectacular job and I think they deserve the recognition of their new titles."

Ellison, previously the only CEO Oracle has ever had, owns 1.1 billion Oracle shares, making him the single largest shareholder. Ellison's slow acceptance of cloud computing and the company's disappointing revenue have produced speculation that Ellison would step down, but Daniel Ives, an analyst at FBR Capital Markets, said the timing of the announcement is a "head scratcher,"

"Larry is leaving Oracle at an interesting juncture, as the company is struggling with growth, and it appears the new product cycle is still a few quarters away from significantly helping the top-line," says Ives. "In our opinion, the company needs [mergers and acquisition] pronto to bulk up its product footprint and get growth back in the Oracle story."

Catz said he wanted to be clear that none of Oracle's daily operations would change as a result of Ellison's resignation as CEO, but Bill Kreher, an analyst at Edward Jones, is a bit wary of the co-CEO dynamic the Oracle founder has left behind.

"Co-CEO structures are typically not ideal," said Bill Kreher, an analyst at Edward Jones. "They're both very independent thinkers who have strong wills. At times they won't agree. But they have worked closely together, and with Ellison. We don't see the day-to-day changing."

Catz and Hurd will now report to Oracle's board, rather than to Ellison, although Ellison is now chairman of the board.