Britain imposed tougher COVID-19 restrictions last week, ordering people to work from home and wear masks in public places, dealing a further blow to a hospitality industry that is already navigating an uneven recovery from the pandemic.
While Wetherspoon has been seeing sales growth across pubs in many towns, places like central London - where remote work and a fall in tourist numbers have hurt patronage - have shown marked declines.
Wetherspoon Chairman Tim Martin has been an outspoken critic of the British government's handling of the health crisis. In a statement, the company said: "The uncertainty, and the introduction of radical changes of direction by the government, make predictions for sales and profits hazardous."
The company added its half-yearly results, for the 26-week period ending late January "may be loss-making or marginally profitable". It reported an annual loss of 194.6 million pounds ($258 million) in October.
Wetherspoon said its pubs, with a few exceptions, are "fully stocked and fully staffed", allaying concerns about staff and product shortages that have hit many British companies.
Shares were trading 4.2% lower at 830.5 pence as of 1210 GMT, their lowest level since November last year.
($1 = 0.7543 pounds)
(Reporting by Aby Jose Koilparambil in Bengaluru; Editing by Amy Caren Daniel and Krishna Chandra Eluri)