BofA chief investment strategist Michael Hartnett said a "sell signal" was triggered for the first time since February as cash levels fell to 4.0% in the latest managers' survey global funds. "We can certainly cope with any difficulties that are thrown our way".
But Downing Street rejected the call and dismissed the idea of a temporary "stand still" period maintaining current arrangements beyond the end of the year.
In the face of the threat of a lack of supplies, Britain is seeking to find a way out of the crisis with France that would allow the movement of goods across the English Channel to resume, which was halted after the spread of a strain that spreads coronavirus infection faster.
"We still can't get our heads around the fact that a trade deal will collapse because of fisheries", he said.
Another popular trade has been shorting the USA dollar and again positioning was looking overextended by many measures, giving the currency some respite on Monday.
Coinciding with the lack of a post-Brexit trade deal ahead of the December 31 deadline, it sent the pound 2.5% lower below $1.32 at one point, though the currency clawed back some of the losses to trade around $1.3285 by 1250 GMT.
In the United States, U.S. Senate Republican Majority Leader Mitch McConnell has said a deal has been reached by Congressional leaders on a roughly $ 900 billion COVID-19 relief bill.
Lead negotiators Michel Barnier and Lord Frost were continuing talks on Monday but the discussions over the weekend were described as "difficult".
Level Playing Field: This is a concept all European Union nations agree to, which ensures member nations can not undercut others by setting their own rules on issues such as the environment, taxation and state aid.
The bloc's lead negotiator Michel Barnier is due to update ambassadors from the 27 European Union nations this afternoon on the state of the negotiations with the UK.
Mr Khan also confirmed he wants the transition period extended.
"We remain very far from an accord", warned a European diplomat, who said that some on the EU-side were weighing whether it was time to walk away.
"It would be unconscionable to compound it with Brexit".
European Parliament had said an agreement was needed Sunday so it could pass through the required approval process by January 1, when the Brexit transition period ends.
But Labour leader Sir Keir did not back the calls for an extension, instead calling on the Prime Minister to deliver a deal.
Ministers are said to be drawing up a plan which would see the deal crashed through the House of Commons and the Lords in a single day, likely on December 30.
