Jonathan Schwartz, Sun’s president, will retain his current position and take over as chief executive, while McNealy will remain chairman and a full-time employee of Santa Clara-based company.

‘‘This isn’t about me. It’s about a big moment in Sun’s history and I’m proud to share that with you,’’ McNealy said on a conference call, adding that the idea to resign as chief executive was his. ‘‘There’s lots more work to do and I’m certainly going to stay around and support that.’’

Sun’s shares surged nearly 9 per cent after the announcement of McNealy’s exit and the $217 million loss that met Wall Street expectations.

McNealy’s 24-year role in charge of Sun ends immediately and coincided with a quarterly report that Schwartz called ‘‘an inflection point’’ in Sun’s turnaround, despite a net loss.

Famous for quips, such as calling Microsoft’s email program ‘‘Lookout,’’ a pun on the Microsoft Outlook name and a reference to the number of viruses successfully targeting it, McNealy turned Sun into a major force in high-end computing as well as more recently offering smaller machines for simpler tasks.

Schwartz, 40, a former software entrepreneur, joined Sun in 1996 when it acquired his company, Lighthouse Design. He has been known as an innovative strategist at Sun, and his trademark ponytail has helped identify him with Silicon Valley’s software design culture.

Although the two men are at much different points on the political spectrum, with McNealy an outspoken conservative, they have complemented each other on business strategy. ‘‘He and I can finish each other’s sentences,’’ McNealy said. ‘‘We’re very aligned.’’

Indeed, partners and customers marveled at McNealy’s staying power. Sun, based in Santa Clara, California, has essentially performed well in three separate eras of computing, stumbling badly at times in the last five years.

The company was founded as a maker of computer workstations for technical and scientific computing applications in the early 1980’s and rose to prominence based on the computing world’s shift away from proprietary mainframes and minicomputers and toward commodity components and open standards.

In the late 1980’s and early 90’s, it built a computing clientele on Wall Street and in corporate computing markets. Finally, the rise of the commercial Internet and the initial explosion of Web server computers swept Sun to peak revenue of $18.25 billion in 2001.

But in 2000 telecommunications companies abruptly stopped spending, and Sun, which had taken to calling itself ‘‘the dot in dot-com,’’ found itself a victim of a financial meltdown in the computing equipment market.

Still, McNealy’s legacy will be not only the company he built, but also a generation of technology leaders who worked under him, including Zander, now the chief executive at Motorola; Carol Bartz, chairwoman of Autodesk, the engineering software firm; and Eric E. Schmidt, chief executive of Google.

‘‘Scott is one of the great leaders of Silicon Valley,’’said Schmidt, who worked for 14 years at Sun. ‘‘I’m just floored that this happened. I believed that he would continue on for the next 50 years.’’

Vinod Khosla, a Sun founder, said Monday that as a leader, McNealy had helped define a Silicon Valley tradition.‘‘Scott is one of those people who build successful companies with passion and a belief system,’’ he added.