The Finish Line Inc. has acquired the assets of an 18-store specialty running chain for $8.5 million, the Indianapolis-based athletics retailer said Thursday morning.

The stores operate under banners including the Greater Boston Running Company, New York Running Company and Texas Running Company, and are in Connecticut, Florida, Maryland, Massachusetts, New Jersey, New York and Texas, as well as the District of Columbia.

Altogether, the stores have annual sales of $19 million.

The chain was founded by competitive runner Gene Mitchell in 1996, and the stores are operated by a group of individual owners. The stores have earned a loyal following among serious runners who prefer expert advice and precision-fitted running shoes, Finish Line said.

Key members of the chain’s management team will remain in place following the acquisition. Finish Line also said it plans to continue operating the stores under their current names.

The purchase enables Finish Line to enter the specialty running business, said Glenn Lyon, the company’s chairman and CEO.

“This acquisition is an important step in our strategic plan to drive growth outside of our core Finish Line business,” Lyon said in a written statement. “We plan to expand the number of stores and develop this chain’s first e-commerce capability, as well as pursue other potential acquisitions in the specialty running business.”

Finish Line expects costs associated with the acquisition will dilute its fiscal 2012 earnings by a penny per share.

Company shares closed trading Wednesday at $20.10 each. The stock hit a 52-week high of $23.64 per share in early July.

Finish Line operates 647 stores across the country.