Shares in software firm VMware have jumped 79% in their first hours of trading on the New York Stock Exchange.
VMware allows one PC to run a number of operating systems
Rising to $59, the hotly-awaited flotation had earlier valued the firm at $11bn (£5.5bn) or $29 per share.
VMware, which makes software that allows computers to run different operating systems simultaneously, enjoys annual revenues of about $1bn.
Its parent, data storage group EMC, floated a 9% stake in the unit, which is a leader in its field.
The company sells a piece of software that lets the different operating systems act as "virtual machines" on one computer.
It allows the different systems to use the computer's resources, such as the processor, sound, graphics, hardware etc, without interfering with each other.
Virtualisation is popular with companies and computer users who need to use software packages that run on differing operating systems, or access legacy files from older systems.
Analysts said VMware's shares were in hot demand - despite the recent general stock downturn - because the company so dominates its fast-growing sector.