SAN FRANCISCO — Ellen Pao, whose court battle against venture-capital firm Kleiner Perkins Caufield & Byers drew focus to simmering gender problems in Silicon Valley, walked away with nothing Friday after a grueling monthlong trial.

A jury of six men and six women in San Francisco Superior Court determined that Pao’s gender wasn’t the main reason the Silicon Valley V.C. firm fired her in October 2012, and failed to promote her before that. Nor did Kleiner take those actions as retaliation for her lodging complaints of gender bias internally, and then suing the firm in May 2012.