The pound rose against the dollar and government borrowing costs fell as investors reacted to the resignation of Prime Minister Liz Truss.
The British currency rose to $1.13 at one point before slipping, but was still higher than early Thursday.
One analyst said the reaction suggested investors were “relieved” by the news, despite much uncertainty remaining.
Business groups said the new prime minister would have to act quickly to restore confidence.
Government borrowing costs rose sharply last month after the government promised big tax cuts in its mini-budget without saying how it would pay for them.
But those costs fell after the Bank of England stepped in with an emergency support program and after Jeremy Hunt reversed almost all the mini-budget measures when he became chancellor.
Hunt will announce spending and tax plans on October 31 when presenting the economic plan, which the Treasury confirmed would go ahead.