Wal-Mart Stores Inc on Thursday tempered its profit forecast for the next two fiscal years due to investments in its online business, and the world's largest retailer said store openings would slow.

The company is holding its annual investor day, where it is expected to report on its progress in e-commerce. Its shares fell 1.9 per cent in premarket trading.

Wal-Mart (WMT.N)  said it expected flat earnings for the year ending on Jan. 31, 2018, with capital expenditures of about US$11 billion. It had previously forecast profit growth.

The company has accelerated its investment in e-commerce and digital efforts from about US$300 million in 2013 to US$1.1 billion this year for a total of about US$3 billion, excluding acquisitions, according to public filings and earnings reports.

Wal-Mart also recently spent more than US$3 billion to buy e-commerce startup Jet.com.

E-commerce accounts for about 3 per cent of Wal-Mart's overall sales.

Wal-Mart said it expected earnings-per-share growth of 5 per cent in fiscal 2019. It previously forecast an increase of 5 per cent to 10 per cent.

The company reiterated its earnings forecast of US$4.29 to US$4.49 for this fiscal year. Excluding items, profit will be US$4.15 to US$4.35 per share, the company said in a statement.