The American grocery giant Kroger is the worst performer in the S&P 500 today, down 14% on guidance that revenues would be down year-on-year.

Kroger is fighting pricing competition from Wal-Mart as well as Aldi, the German discount grocer that is now expanding in the US. Supply-chain management may not be as sexy as artificial intelligence, but it is the beneficiary of a wide range of innovations.

The global grocery giants have a price advantage and are squeezing margins. This is yet another example of the “idiosyncratic” price declines that have bedeviled the Federal Reserve’s Phillips Curve model. Fed Chair Yellen still believes that more employment means more inflation. Tell that to Kroger shareholders.