Maersk Wary Over Outlook

COPENHAGEN—Shipping and oil company A.P. Moller-Maersk A/S warned Wednesday that new shipping capacity and deteriorating world economic prospects are pressuring freight rates, and said it isn’t sure when they are likely to recover.

The Danish company issued a cautious forecast for the full year, after posting a 5.8% decline in first-half net profit. Maersk, which operates the world’s largest container-shipping company, Maersk Line, didn’t include any freight-rate improvement for the second half in its adjusted full-year forecast, Maersk Chief Executive Nils Smedegaard Andersen said.

“Our competitors are very nervous,” Mr. Smedegaard Andersen said. “They’ve bought a lot of new ships …