LONDON (Reuters) – Tesco, Britain’s largest retailer, was the only one of the country’s big four grocers to grow sales in the last 12 weeks, increasing its sector dominance in the run-up to Christmas, data from market researcher NielsenIQ showed on Tuesday.

It said Tesco’s sales rose 0.4% year-on-year in the 12 weeks to Nov. 6, increasing its market share by 0.2 percentage points to 26.6%.

In contrast smaller rivals Sainsbury’s, Asda and Morrisons saw sales fall 3.1%, 2.4% and 4.7% respectively, and all lost market share.

NielsenIQ’s data echoed figures from rival researcher Kantar last week.

Last month, Tesco reported a 16.6% jump in first half profit and raised its full-year earnings forecast despite supply chain disruption.

NielsenIQ said total UK grocery sales fell 2.0% in the four weeks to Nov. 6 versus high comparative numbers ahead of a second national COVID-19 lockdown last year.

Sales were, however, up 4.9% on the same period in 2019.

The researcher noted that in-store visits to supermarkets were up 6.5% compared with last year over the four week period, equal to 28 million more visits.

In contrast, the online share of sales fell to 12.2%, down from 12.6% in the previous four weeks.

($1 = 0.7443 pounds)

(Reporting by James Davey; Editing by Mark Potter)