Questor share tip: Avoid Bumi until the situation is clearer Bumi owns 29pc of Indonesian-listed Bumi Resources, Asia's biggest exporter of coal that is used in power stations. London-listed Bumi is controlled by Indonesian investors, including the Bakrie family. Bumi also owns 85pc of Berau Coal. Nat Rothschild brought the business to London by reversing it into his cash shell Vallar. The shares were initially listed at £10, so with shares now at less than a fifth of that, a significant amount of any initial investment into Mr Rothschild's cash shell is underwater. Bottom-fishers have started to nibble after the shares plunge after the accusations earlier this week, but Questor thinks this is a risky gamble. Bumi's subsidiary has to refinance between $300m and $400m of debt in 2013, according to credit ratings agencies. This could prove a challenge - and has prompted Moody's and Standard & Poor's to cut their ratings on Bumi Resources. The subsidiary has about $3.95bn of debt in total. Although the shares are now a fraction of what they were once worth - and there is no dispute over the quality of the actual coal mines themselves - there is still a lot of risk, with allegations of financial irregularities and the chance of a funding issue. Some have speculated over a potential rights issue. However, would investors who have lost more than 80pc of their initial investment want to throw more money at the business? The investigation will take a few weeks. Bumi will then have to decide what it wants to do with its 29pc stake in Bumi Resources. It either needs full control of Bumi Resources or dispose of its holding. Until there is more clarity, investors should avoid the shares.