Bermudian-based White Mountains Insurance Group has agreed to invest up to $1 billion of fresh capital into Ark Insurance Holdings Ltd and acquire a majority stake in the Lloyd’s of London insurer.One of the results of the deal will an upgrade of Ark’s existing Bermuda operation into a Class 4 reinsurer – the largest category under the Bermuda Monetary Authority’s licensing regime – and the hiring of new underwriters on the island. Ark is the parent company of Ark Syndicate Management Ltd,