What's going on?

On Thursday, Kroger � the largest US supermarket chain � reported disappointing sales growth in its latest quarter, sending its shares crashing 10%. Clean up in aisle four, please.

What does this mean?

Kroger�s using technology to change how it operates in order to be more competitive � and putting these changes in place is causing disruption. Sales growth fell short of expectations because it was changing the layout of its stores, which meant that customers couldn�t always find what they were looking for � leading them right into the arms of other grocers.

Why should I care?

For markets: Investors are putting the brakes on Kroger�s restart.

When a company has difficulties and restructures (like Kroger, last year), investors often want to see proof it�s back on the right track before they invest (they sometimes call such companies a �show me story�). Kroger�s shares had risen almost 40% since March, thanks in part to striking a major tech deal with Ocado. However, investors may be selling once again because they�re worried shoppers won�t return to Kroger if there are cheaper (Aldi and Lidl) or more convenient (Instacart) ways to get their groceries. Kroger might become a �show me� story yet again.

The bigger picture: Supermarkets are super-changing but it�s not all bad.

Most big supermarkets are making big moves to compete with cheaper (and Amazon-ier) alternatives and changing shopping habits. Walmart�s digital investments paid off last quarter. And French grocer Groupe Casino has teamed up with Ocado. Major investments usually mean higher costs and lower profits, but there�s some hope: British chain Morrisons reported upbeat results on Thursday, growing quarterly revenue by 6% more than a year ago � well above estimates � partly helped by its own tie-up with Amazon.