Validus Holdings Ltd has extended the deadline for its offer to buy Transatlantic Holdings Inc to 5pm Eastern time on November 25.The confidentiality agreement and discussion period between the two insurers ended on Monday.Validus said yesterday that it was still in discussions with Transatlantic, but that there was no guarantee that a deal would be completed.Validus is one of several reported bidders for Transatlantic, which was in discussions with Omaha, Nebraska-based Berkshire Hathaway Inc’s National Indemnity Co, but Transatlantic rejected its $52 per share offer and Berkshire’s refused to up the bid.Two other, unnamed bidders are also in discussions with Transatlantic, believed to include a group of investors led by former Gen Re Corp CEO Joseph Brandon, and a joint bid from Bermuda-based Enstar Group Ltd and CV Starr & Co was made last month.A planned merger between Transatlantic and Allied World Assurance Co collapsed in September.