Times Mirror shareholders approved an increase in the number of authorized common shares to 550 million from 80 million, including two new classes of stock with different voting powers from existing common stock. Nearly 67% approved the anti-takeover device, according to a preliminary count. Under the plan, the board of directors can issue up to 100 million Class B shares, which have 1/10th of one vote per share, and up to 150 million Class C shares, which have 10 votes per share. The board has no plans to issue Class B shares but could vote to issue Class C shares to holders of existing Class A shares by the end of the year, Times Mirror said. Class C shares must be converted into Class A shares if sold, thereby encouraging long-term stock ownership.