By Lars Mucklejohn Insurance giant Prudential has launched a multi-billion-dollar share buyback as part of plans to enhance shareholder returns. The company said it would buy back $2bn (£1.6bn) of shares over the next two years. Shares repurchased under the programme will be cancelled. Separately, the company laid out its plans for capital returns going forward. Prudential said it would seek to operate with a free surplus capital ratio of between 175 per cent and 200 per cent and would return any additional capital to investors. At the end of 2023, the group said its free surplus ratio was 242…