IBM, Sun Seal Server Partnership

The deal would become more valuable to IBM if the companies move forward with their plans in progress to make Solaris available on high-end IBM servers and mainframes.

Shares of IBM closed the day down $1.54, or 1.4%, to $109.69.

For its part, Sun stands to benefit by opening a new path to introduce its Solaris operating system to the world of companies using IBM servers, which compete with Sun's own hardware.

The deal underscores the pragmatism of Schwartz, who took the helm in 2006 and aims to spark revenue growth by appealing to a broader set of customers.

One of Schwartz's first moves as CEO was a decision to use microprocessors from long-time rival Intel (INTC Quote) in certain Sun servers.

Thursday's move takes the concept a step further by making Sun's flagship operating system available to a broader swath of customers beyond those using Sun machines.

"We want to make sure we're open to as much market opportunity as possible," said Schwartz during the conference call.

Sun shares rose 7 cents, or 1.5%, to $4.72.