Investors say the UK-EU trade deal leaves the UK facing many economic uncertainties.
Global shares ticked up on Monday after US President Donald Trump signed into law a $2.3-trillion pandemic aid and spending package he had until now refused to sign.
Futures contracts for the US S&P 500 share index last traded up 0.4 percent.
The futures had earlier reversed losses after a cryptic tweet by Trump – “Good news on Covid Relief Bill. Information to follow” – helped offset worries about a further delay in stimulus spending.
Japan’s Nikkei 225 share index inched up 0.4 percent. MSCI’s broadest index of Asia-Pacific shares outside Japan rose 0.2 percent, though trade is slow with many markets still closed for holidays.
“It is positive for markets that we no longer have a chaos over stimulus, considering there was a chance of a partial government shutdown,” said Masahiro Ichikawa, chief strategist at Sumitomo Mitsui DS Asset Management.
“But on the other hand, markets have talked about that stimulus for a long time and I would say most of it has been already priced in.”
Trump had refused to sign into law the government spending and pandemic aid package that Congress passed, demanding stimulus checks for struggling Americans be increased.
Trump’s threat to not sign the package had already shuttered an emergency unemployment aid programme and threatened a partial federal government shutdown at midnight on Monday.
US bond yields edged up in its first trade after Christmas, with the 10-year US Treasuries yield rising 0.6 basis points to 0.930 percent.
Rising bond yields signal growing economic optimism among investors.
The rollouts of COVID-19 vaccines are also bolstering hopes of more economic normalisation next year, with Europe launching a mass vaccination drive on Sunday.
That offset alarms over a new highly infectious variant of the virus that has been raging in the southeast of England and was confirmed in many other countries, including Japan, France and Canada, over the weekend.
Key global currencies were little changed.
The euro traded at $1.2204, slightly below its two-and-a-half-year high of $1.22735, while the Japanese yen changed hands at 103.56 per dollar.
The British pound traded at $1.3565, not far from a two-and-a-half-year high of $1.3625 hit earlier this month after the UK and the European Union reached an agreement on trade framework after Brexit.
Bitcoin extended gains over the weekend to reach a new high of $28,377.94 before stepping back to $26,457.32, bringing the total value of the cryptocurrency in circulation to more than $500bn.
Oil prices edged lower, with US crude futures down 0.8 percent at $47.85 per barrel.