Harold C. Simmons boosted his stake in Sea-Land.

An attorney for the Dallas invester said Simmons has increased his stake in the company to 22.1% from 18%. He now owns a total of 5,144,831 shares of Sea-Land Corp. The additional purchases were made at prices ranging from $24.25 to $24.75 a share, the attorney said. The company has about 23.2 million shares outstanding. Sea-Land is an ocean shipping-container firm based in Menlo Park, N.J.