Swiss drugmaker Novartis has finally wrapped up its long-awaited buyout of U.S.-listed Alcon in a $12.9 billion deal after sweetening its original offer with a cash element.

Novartis has been trying to clinch 100% ownership in Alcon since the start of the year, but its original offer of 2.8 Novartis shares for each Alcon share met stiff resistance from Alcon shareholders.

The Basel-based group is hoping the Alcon deal will help it diversify and protect it against patent loss on big selling medicines such as blood pressure drug Diovan.

Novartis said the merger consideration will now include up to 2.8 Novartis shares and if necessary be topped up with cash to ensure that each Alcon shareholder gets $168.

The group added that if the value of 2.8 Novartis shares is more than $168 the number of Novartis shares will be reduced accordingly and that a share buyback would be reactivated to minimize dilution to Novartis shareholders.