The UniMark Group, Inc. (OTC Bulletin Board: UNMG) announced yesterday that its registration statement for a rights offering to sell up to 10,273,972 shares of its common stock at $ .73 per share to its shareholders of record on May 22, 2001, has been declared effective by the Securities and Exchange Commission. Accordingly, the Company is now mailing a rights offering prospectus to each shareholder of record.