Frates’ group hiked its Kaiser Aluminum stake.

A group led by Oklahoma investor J. A. Frates increased its Kaiser Aluminum holdings to 19.95% of the Oakland-based company’s common stock from 18.6%, the group said in a filing with the Securities and Exchange Commission. The Frates group said it bought 614,000 shares Jan. 29 for $17.50 a share, bringing the group’s total holdings to 8,802,950 shares of Kaiser Aluminum. The Frates group is trying to oust Kaiser Aluminum’s board of directors and take over the company.