Fears have been raised that Punch Taverns may have to raise more funds after its US bond insurer Ambac said it may file for bankruptcy,writes Ewan Turney. Ambac said it could file for bankruptcy before the end of the year and Seymour Pierce analyst Hugh-Guy Lorriman said this could affect Punch. "It may be that the responsibility of Ambac as insurer passes to another body which is more active in protecting its interests. "It may be that the insurance simply disappears ad that the immediate result is the downgrading of the underlying Punch debt by rating agencies. "What is the likely result of this? Either debt holders demand additional equity injection to prevent longer term default probability, or debt holders agree on some form of "haircut". "The situation is volatile and remains high risk." It comes after Morgan Stanley analyst Jamie Rollo said that Punch shares could be worth as little as 5p in the worst case but could reach 110p if they recovered. Shares in Punch opened today at 69.75p. Yesterday, Punch chief executiveIan Dyson acquired 100,000 shares for £65,850 — 65.85p.