The Herbert Quandt family said it had...

The Herbert Quandt family said it had more than doubled its stake in Minneapolis-based Data Card Corp., to 97%, following the terms of an agreement announced this summer. Data Card, which employs 2,880, is a worldwide supplier of plastic credit cards and equipment required to emboss and electronically encode the cards. The Quandt family in August acquired 43% of Data Card from the previous majority shareholder, National Computer Systems Inc. National agreed to sell its stake at $17.50 a share, or about $74 million, and the remaining shares were to be purchased at the same price. The Quandt family’s total investment in the company is about $173 million.