SuperValu is just marginally behind Tesco for sales in Ireland for December, January and February.
The latest supermarket share figures from Kantar worldpanel show that in the 12 weeks to March 1, Tesco's share was 25%.
SuperValu was at 24.9% with Dunnes at 23.4%.
Discount supermarkets Aldi and Lidl had a total share of 15.7%.