The Zurich-based company said it had bought 11.2 million shares, equivalent to 3.21 percent of its outstanding shares, at an average price of 89.17 francs per share.

The buy-back was established to return capital to shareholders, said the company, which is due to report its full-year earnings on Thursday.

(Reporting by John Revill,; Editing by Tassilo Hummel)