Apple Inc. Chief Executive Tim Cook this week reaped the biggest chunk so far of the mega-stock grant he received when was named CEO in 2011.

In a Securities and Exchange Commission filing on Friday, Mr. Cook said he had received 1.26 million shares of Apple stock, valued around $135 million, that previously were restricted. He now has hit the halfway point of a stock-compensation plan that could see him awarded seven million shares by 2021.

Mr. Cook earned the bulk of the shares—980,000—by remaining CEO for five years. He earned the additional 280,000 shares because Apple stock outperformed more than two-thirds of the companies in the S&P 500-stock index over the past three years. Read More