0942 ET - Walmart shares fall 8.4% after the retailer's updated outlook for the year failed to impress investors. But CFO John David Rainey says on a call with analysts it's important to remember the new forecast comes as the company faces more than $2 billion of incremental costs this year tied to higher fuel prices. The new guidance also comes against an arguably softer consumer environment than in February, when Walmart initially issued its FY outlook, Rainey adds: "As such, we feel it's prudent to remain cautious by only raising the guide modestly."