Five years after selling Reebok to Adidas for $3.8 billion, Paul Fireman’s private-equity firm is backing Newton Running Co., the Boulder, CO. maker of “natural” running shoes. Boston-based Fireman Capital Partners has invested between $10 million and $20 million in the 4-year-old company, managing general partner Dan Fireman told the Boston Herald.

It’s the sixth investment by the firm, whose portfolio also includes Hudson Jeans, Evolution Fresh, Serena & Lily, IdeaPaint and Pilla.
 
“Were going to have a significant stake,” Fireman told the newspaper, adding that both he and his father will be very active in Newton Running. “Well have influence over the company, its direction and operations. It’s great when you can take those skill sets that youve learned and done for years and apply them to a company that you really understand.”

Newton Running reportedly generates about $20 million in annual revenue and is growing at a rate of 100 percent per year. Newton Running’s product offerings also will be expanded to include lower-cost shoes in the $80 to $100 range. The company’s shoes currently retail for $135 to $175.

Dennis Baldwin and Steve Liggett, who ran product development, manufacturing and marketing for 15-plus years at Reebok, will represent Fireman Capital on the Newton Running board.