The Frates group hiked its Kaiser Aluminum stake.

The investor group, led by Oklahoma investor Joseph A. Frates, increased its holdings in Kaiser Aluminum stock to 12.3 million shares, or about 27.53% of the company. The group, which tried to take over Kaiser earlier this year, previously had a 26.4% interest. A spokesman for the group said the investors are interested in buying more stock, based on the price and the group’s availability of funds. The group continues to monitor Kaiser Aluminum’s performance and could decide to mount another takeover attempt or sell its shares, he said.