General Motors' shares, already at their lowest level in half a century, fell by almost 10 per cent by midday yesterday after Merrill Lynch downgraded its recommendation for the stock to "underperform" from "buy" and said that "bankruptcy is not impossible".

Not all analysts share that view, and Rick Wagoner, GM's chief executive, referring to the company's liquidity position, told the Financial Times in an interview last month that "under any scenario we see, we're good until the end of the year".