ELAN Corporation is to exercise its option to acquire 100 per cent of the outstanding stock of Advanced Therapeutic Systems (ATS) at $36 (£22) per share at a total cost of $141 million. The transaction will be completed before the end of October and Elan will incur a one time charge of about $141 million in the quarter to September, 1996. ATS was formed in May 1993 and subsequently funded through a rights offering to Elan shareholders.