Walmart and Costco should gain as soaring diesel costs push consumers to trade down. Diesel is up 35% in 40 days and moves the trucks that stock every US shelf, and though America produces about as much oil as it uses, oil trades globally, so Europe's shortage hits US prices. Retailers must raise prices and lose volume or absorb costs and miss guidance. Discounters are big enough to absorb the shock and win trade-down shoppers; packaged food, staples and restaurants look best avoided. x.com x.com x.com x.com x.com