Kleiner Perkins, the defendant in a high-profile discrimination lawsuit against former partner Ellen Pao, is due to gain less than a third of its claimed costs following a tentative ruling by a California judge on Wednesday.

Harold Kahn, superior court judge, told the Silicon Valley venture capital firm that it should receive $276,000 (£173,000) of the $973,000 (£611,000) it sought for defending itself against accusations that it had fired Pao because of sexism.

In his reasoning he said the "allowable amount" of the costs had to be limited to work "reasonably needed to respond to Ms Pao’s claims", excluding extra work that Kleiner Perkin’s advisors thought might have helped it make its case that Pao was dismissed because of incompetence.

Kahn’s judgement also sided with Kleiner Perkins by accepting that its previous offer of settlement to Pao before the trial, which came to nearly $1m (£630,000), was made in "good faith" and not a "token" offer, as she had described it.

Christina Lee, communications partner at Kleiner Perkins, said in a statement: "This tentative ruling recognises that our settlement offer was reasonable and made in good faith.

"It also recognises the cost rules still apply when a plaintiff refuses a reasonable settlement offer and forces the parties to go through an expensive trial."

Pao said she would appeal, and according to a court filing earlier this month by Kleiner Perkins had offered to drop the case for $2.7m.

The tentative ruling comes as another piece of bad news for Pao, who is facing backlash for her role as interim chief executive of the content aggregator Reddit over claims her policies were infringing on the site’s historic commitment to free speech.

Despite her loss the case still highlighted the gender imbalance within Silicon Valley, and coincided with firms like Google, Twitter and Facebook releasing figures on the sex and ethnic makeup of their workforces.

Image – Ellen Pao by Christopher Michel