NEW YORK — Best Buy Co. reported a sales shortfall for the fiscal second quarter and trimmed its annual sales forecast, blaming uncertainty surrounding an escalating trade war with China heading into the holiday shopping season.

Shares of the retailer fell 8 percent in afternoon trading Thursday.

Best Buy has succeeded in holding off increasing competition from Amazon and other players by expanding its online business, speeding up deliveries and adding more services to enhance its relationship with its customers.

That reinvention was spearheaded by Hubert Joly, who was named CEO in 2012 but stepped down this year. Under Barry, who took over the job in June, Best Buy is continuing to focus and expand on those initiatives.