JUPITER, Fla., Sept. 17 -- Photronics Inc. and Align-Rite International Inc. have signed a definitive agreement to merge the two companies in a stock transaction that will create the world's largest merchant photomask supplier. The merger is valued at approximately $115 million and will accrete to earnings.Under the terms of the agreement, which was unanimously approved by both companies' boards of directors, shareholders of Align-Rite will receive the equivalent of $23.09 per share in Photronics common stock. The number of shares to be exchanged -- subject to certain limitations -- will be calculated based on Photronics' average share value over the course of the 20 days preceding the three days before Align-Rite's shareholder meeting. The companies expect Align-Rite shareholders to hold approximately 16 percent of Photronics' shares after the merger has concluded. The transaction will be accounted for as a pooling of interests. In a related move, Photronics will resell the one million shares it acquired under its share repurchase program, which began in October 1998.