THE Prudential yesterday said it had agreed to sell its reinsurance business in a £1.74 billion sterling deal, fuelling speculation the British life insurance giant is poised to make a takeover offer for a building society. Earlier this summer, the Pru said it would float part of Mercantile & General as a separate company on the stock market. But the agreed sale announced yesterday with Swiss Re for £1.74 billion sterling cash together with a special dividend of £50 million, brings forward the date when the Pru is likely to receive the cash proceeds.