Boeing shares could fall 15 percent if sales slow: Barron's

Airlines and leasing companies are using planes longer and delaying orders for new aircraft, the publication said.

Low oil prices have also reduced the need to buy updated, more fuel-efficient planes, it added.

Boeing generates roughly two-thirds of its revenue from commercial aircraft, and the remainder from its defense business.

Demand for Boeing's 737 planes remains strong despite competition from Airbus Group SE and Bombardier Inc .

However, its 777 and 787 models are at greater risk, Barron's said.

Boeing's 787 could face write downs because initial costs were high and sales have slowed, it added.

(Reporting by Olivia Oran; Editing by Alan Crosby)