FILE PHOTO: FILE PHOTO: A Walmart store in Woodstock, Georgia, United States

A shopper is seen in the aisle of a Walmart store in Woodstock, Georgia, U.S., June 28, 2018.

Walmart kicked off U.S. retailers' reporting season on Tuesday with robust fourth quarter results after inflation-squeezed shoppers flocked to its stores, and said it would buy smart-TV maker Vizio for $2.3 billion.

Shares in the retail giant rose 3% in premarket trading after it also gave an upbeat annual sales forecast and announced a 9% rise in its dividend, the biggest increase in more than a decade.