How nervous are investors about the US debt ceiling?

Negotiations to prevent the US government from running out of money are headed down to the wire.

The Treasury says Congress must agree to raise the debt ceiling by 1 June or the US will run out of cash to pay its bills, resulting in economic disaster.

Top congressional Republican Kevin McCarthy says his party and the Democrats remain "far apart".

Fitch, one of the big credit ratings firms, has said the impasse could prompt it to lower America's rating.

So with just over a week left - including a...