Shares in BP PLC are falling again in London trading after the U.S. government announced a criminal investigation into the Gulf of Mexico oil spill.
The stock is down 3 percent at 416.45 pence ($6.11) in morning trade on Wednesday -- extending a 13 percent drop on Tuesday.
There is mounting speculation about London-based BP's future as it struggles to contain the spill and after its revelation that its costs are nearing $1 billion.
BP has lost some $75 billion in market value since the Deepwater Horizon rig exploded six weeks ago and analysts expect damages claims to total billions more.
The stakes have been raised even higher after the U.S. government opened criminal and civil investigations -- without specifying which companies or individuals might be targets.