Apache's server software powers 36 percent of corporate Web sites, according to the study. Microsoft and Netscape trail with 21 percent apiece.
But Netscape's share of the market increases along with the size of the surveyed Web sites' company. For companies with annual revenues of more than $1 billion, Netscape has a 38 percent penetration, compared to Apache's 24 percent and Microsoft's 21 percent.
SiteMetrics, which measures the visibility and performance of corporate Web sites, surveyed 25,000 Web sites owned by the largest U.S. businesses. It is the first such study from SiteMetrics.
The study found 345 different software versions from 107 suppliers in use. Apache, Microsoft, and Netscape together took 78 percent of the market, and NCSA, Stronghold, and WebSite picked up most of the remaining sites with 4 percent each.
Apache dominates ten of the 14 industries included among SiteMetrics' survey pool. Microsoft leads in the computer industry with 31 percent penetration, and Netscape leads the consulting industry with 30 percent.
Apache leads and Netscape trails by greater margins in the market overall, according to the latest numbers from Netcraft. Without limiting the survey to corporate users, Apache leads with 46 percent, followed by Microsoft with 21 percent, and Netscape with 5 percent.