The world's largest company, Wal-Mart Stores Inc, on Thursday reported a 3.3 per cent rise in April same-store sales and said total sales climbed 9.3 per cent year-on-year to $17.6 billion. The Arkansas-based company added that comparable sales at its discount stores climbed 3.2 per cent last month, while sales at its warehouse unit, Sam's Club, rose four per cent in April.