Shares fell 5.5 percent immediately after the news was announced, before rebounding, hovering at just over 1 percent down by early afternoon.
The company's founder and chief executive Bjørn Kjos blamed price competition with other carriers for its falling profitability.
"There’s strong competition in the market and many affordable tickets available, which benefits the customers," he said in a statement. "At Norwegian, we are prepared to meet the competition by introducing even more brand new aircraft to the fleet, expanding the route network and adding new destinations to the route map. New aircraft with lower fuel burn is key to keeping costs down and continue to offer more low-fare tickets."
Some 1,527,099 passengers flew with Norwegian in February, a 22 percent leap on the same month last year, as it brought in long haul flights to Thailand and the US, using the new Boeing 787 Dreamliner plane.
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The company expects to take delivery of four new 787 Dreamliners during the first half of 2014, as well as 15 new 737-800 aircraft.