Kilroy Realty Corp. increased a stock offering due to investor demand, boosting the proceeds to $221 million.

The offering was raised to 6 million shares at $38.25. When the company announced the offering on April 5, it planned to sell only 4.5 million shares but increased the allotment due to demand from investors.

The company plans to use the money for the $100 million purchase of four office buildings in the Seattle suburb of Kirkland. The remaining proceeds will pay down an unsecured revolving credit facility and go toward working capital.

Kilroy is a Los Angeles-based real estate investment trust that buys office and industrial buildings in West Coast cities. It owns about 10.4 million square feet of rentable office space and 3.6 million square feet of rentable industrial space.

Shares of Kilroy gained 23 cents, or less than 1 percent, to trade at $39.31 by mid-day on the New York Stock Exchange.