In the global race to build the next generation of supercomputers -- exascale -- there is no guarantee the United States will finish first. But the stakes are high for the U.S. tech industry. Today, U.S. firms -- Hewlett-Packard, IBM and Intel, in particular -- dominate the global high-performance computing (HPC) market. On the Top 500 list, the worldwide ranking of the most powerful supercomputers, HP now has 39 percent of the systems, IBM 33 percent, and Cray nearly 10 percent.