Donald Trump heralded a "big victory" for the Republicans in the US midterm elections despite losing control of the House of Representatives.
The Democrats took control of the lower chamber on a dramatic night, potentially making it harder for Trump to pass legislative plans over the next two years.
The dollar weakened as a result, with the pound and euro both making gains and global stock markets rallying.
But the Republicans strengthened their control of the Senate, giving the Presidents cause for celebration.
Trump, taking to social media, said: "Received so many congratulations from so many on our big victory last night, including from foreign nations (friends) that were waiting me out, and hoping, on trade deals.
"Now we can all get back to work and get things done!"
He also hit back at suggestions the Democrats would use their majority of the House to request the President's tax returns and investigate his policies.
He said: "If the Democrats think they are going to waste Taxpayer Money investigating us at the House level, then we will likewise be forced to consider investigating them for all of the leaks of Classified Information, and much else, at the Senate level.
"Two can play that game!"
The pound has gained 0.5 per cent on the dollar, climbing to a three-week high of $1.316 and the euro also rose 0.5 per cent to $1.149, its highest this month.
The FTSE 100 climbed 1.1 per cent as the weakening dollar boosted the mining sector – Antofagasta, up 3.7 per cent and Anglo American, up 3.3 per cent were among the biggest risers, while Rio Tinto and BP shares also jumped.
European markets also rallied with the Euro STOXX index - across 17 countries - up 1.2 per cent.