It looks like any euphoria felt by currency traders about Friday's High Court ruling over Brexit was short-lived: The pound was down more than one per cent against the dollar in early trading this morning, dropping below $1.24.
The pound fell 1.01 per cent to $1.2391 as traders' faith in Hillary Clinton was restored after she was cleared of wrongdoing by the FBI.
Sterling also fell against the euro, dipping 0.27 per cent to €1.1207.
Analysts suggested the slide could also be attributed to further revelations over the weekend about Brexit.
"If there still is the perception that the UK may after all be faced with a 'soft' Brexit, then sterling should find some support," Jane Foley, senior strategist at Rabobank, told Reuters.
"But the outcome of the US election is clearly dominant now."
The FTSE 100, meanwhile, rallied - led by HSBC, whose shares jumped 4.37 per cent to 620.7p despite figures published this morning showing pre-tax profits fell 86 per cent to $843m in the three months to the end of September.
“Markets are back in full risk-on mode this morning after the FBI said it will take no further action against Hillary Clinton," said Neil Wilson, markets analyst at ETX Capital.
"For the [FTSE 100] there are two things at work. Part of this is a broader rally in equities – European stocks are up and US stock futures point to a sharply higher open for Wall Street and an end to nine-straight days of losses for the S&P 500.
"But we’ve also got to look at the fall in sterling. Driving the FTSE 100 higher today are the big foreign-earners like drug companies, miners, oil producers and HSBC – the bank makes up over five per cent of the FTSE 100 by index weight so today’s four per cent rise is helping the blue chip index in no small way.
"If Trump wins and the dollar slides, the FTSE could easily hand back these gains and quickly. A stronger pound versus the dollar coupled with a broader risk-off sentiment could spark a big selloff. A 10 per cent plunge for US stocks might be expected as this would take us back to February’s lows."