SAN FRANCISCO — Silicon Valley billionaire and early Google Inc. investor David Cheriton lost in court Wednesday to friend-turned-rival Andy Bechtolsheim.

It's Bechtolsheim's company, not Cheriton's, that owns 114 files at the center of a contentious bench trial fought in September, a Santa Clara County Superior Court judge found. The preliminary ruling protects Bechtolsheim's company, network switch manufacturer Arista Networks Inc., from grabs for its intellectual property by sister company OptumSoft Inc., run by Cheriton. The two companies had peacefully shared office space and IP under a software-sharing agreement until tensions came to a head in 2010, at which point they looked to the court to draw a line separating the two companies' property.

“The court finds that OptumSoft's interpretation of the agreement would impose obligations on Arista which were not bargained for or agreed to when the agreement was entered into,” Santa Clara Judge Peter Kirwan wrote in a proposed statement of decision. “OptumSoft's broad interpretation of the scope of the ownership provision is simply not supported by the language of the agreement or by the subsequent conduct of the parties in the years that followed.”