Tesco might have hoped for a better reaction to its news that it has returned to profit this morning than for investors to send its share price tumbling.
Perhaps it was the relatively cautious statement given by chief executive Dave Lewis, or the fact that while profits were above consensus expectations, sales missed by a touch.
Or maybe it's the fear that the fundamental issues plaguing the sector – ie the price wars brought about by challengers such as Aldi and Lidl aren't going anywhere.
Either way, Tesco's share price was down 4.9 per cent in mid-morning trading, making it the biggest faller on the FTSE 100 this morning.
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And the UK's biggest retailer appears to be having an impact on rival grocers' share prices too.
Sainsbury's was down 1.1 per cent, while Morrisons was down 1.5 per cent.
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But not everyone was struggling. Delivery group Ocado's share price was up 1.4 per cent.