Wal-Mart Stores Inc., the world's largest retailer, posted first-quarter earnings that missed analysts' estimates after U.S. sales grew more slowly than projected and currency fluctuations ate into profit.

Earnings amounted to $1.03 a share, excluding some items, the Bentonville, Arkansas-based company said in a statement Tuesday. Analysts had predicted $1.05 on average, according to data compiled by Bloomberg. Revenue also was light last quarter, with the company's U.S. supercenters and Sam's Club locations posting slower growth than estimated.

Chief Executive Officer Doug McMillon faces the dual challenges of reviving growth at home and contending with the strong dollar overseas, which has whacked the value of its international revenue. Currency effects are now expected to reduce sales by $14 billion this year, up from a previous projection of $10 billion. Wal-Mart gets more than a quarter of its revenue from international markets.