The German firms remained the fastest growing in the sector, with sales up 14.2% and 11.4% respectively, but Kantar said customers were not completely deserting traditional players.
Edward Garner, director at Kantar Worldpanel, said 94% of Aldi and Lidl shoppers still visit one of the four every four weeks.
“However, consumers’ spend is increasingly being shared with other growing outlets which also include Waitrose, the Co-operative and Iceland and average household spend for the big four has dropped by 2.9%,” Garner added.
Waitrose’s market share hit an all-time high of 5.3% as sales grew by 2.1%.