READ: Sainsbury's posts second straight quarter of underlying sales decline although full-year profit beats forecasts Kantar Worldpanel on Wednesday said Sainsbury's saw its market share fall by 0.5 percentage points (ppts) to 15.2% while Asda lost 0.2 ppts to 15.2% in the 12 weeks to May 19. "With the CMA ruling against the proposed merger now behind them, Asda and Sainsbury's are neck and neck in the number two position this period as overall sales at Asda fell 0.2% despite online growth of 10.7%," said Chris Hayward, consumer specialist at Kantar. Tesco PLC ( LON:TSCO ) remained the number one supermarket, keeping a market share of 27.3%.