NEW YORK—Adidas AG is more successful than ever in the U.S., but its new boss isn't satisfied yet.

Kasper Rorsted, who became Adidas's chief executive in October, said in an interview that the company's list of North American challenges was "very long."

Adidas, which has gone through years of sliding sales and numerous attempts to improve its image in the U.S., is finally enjoying strong momentum in the region. This year it has raised its financial outlook four times. It also recently surpassed Under Armour Inc. in quarterly North American sales. Data from analysts NPD Group shows that Adidas's share of the U.S. athletic footwear market so far this year is 7.1%, up from 4.3% in the same period last year.

Mr. Rorsted, known to investors for his ability to cut costs and improve margins, said much work remains.

"We are very happy with the progress, not with the position," he said Wednesday, adding: "I don't think there will be any kind of complacency from us in the U.S."

Immediately after taking over, Mr. Rorsted told investors that the North American market was his priority. When presenting the company's third-quarter results in November, he announced his first big business decision: a revamp of Adidas's Reebok brand in North America.

Reebok's performance in the region had lagged for several years and was dragging down Adidas's overall earnings, he said at the time.

"Reebok was diluting the growth and the margins," he said Wednesday. "We need to address errors, make sure that where we are, we have a business that we are happy with."

Restructuring Reebok will include slashing approximately 150 jobs and removing all non-Reebok assets from the company's location in Boston, he said.

Separately, he said he wanted to continue on the path set by his predecessor, Herbert Hainer, of concentrating on American sports and the U.S. performance segment. He pledged to pay particular attention to basketball and running, which today are among Adidas's slowest- and fastest-growing business segments, respectively.

Zuzanna Pusz, a Berenberg analyst, said the U.S. market should be a key driver of profitability improvement for Adidas. "There will be big pressure on Rorsted to balance the top-line growth and the margin development," she added.

Since replacing most of its U.S. management team in 2014 and hiring its current North American boss, Mark King, Adidas has also worked to improve its relationship with big sporting-goods chains, which drive the majority of manufacturers' revenues.

When Mr. King took office, big retailers including Foot Locker Inc. and Dick's Sporting Goods Inc. expressed limited enthusiasm for Adidas. Dick's CEO Edward Stack said on an earnings call last year that the Pittsburgh-based retailer would clear shelf space from Adidas to make room for its own casual athletic line by "American Idol" singer Carrie Underwood.

Mr. King said his reaction at the time to Mr. Stack's comments was "'What, you don't love me anymore?'"

He added that Dick's and other retailers had trouble envisioning growth with Adidas back then, but the sentiment had reversed.

"I think retailers follow the money and the hot brand and the opportunity for growth," Mr. King said. Today, he said, "the products are better, the brand is stronger and our relationship is better." Dick's didn't respond to a request for comment.

Adidas is also working to revamp its own retail network in the U.S., including Thursday's opening of a flagship store on New York's Fifth Avenue, complete with concessions and stadium-style seating to encourage shoppers to relax and hang out.

Mr. Rorsted said he didn't want to specify financial goals yet, but he expected the U.S. market to grow "over-proportionally" compared with the rest of the company's business. Adidas's online business in North America had more than doubled in the course of the year, he said.

Mr. Rorsted added that he planned to continue to "over invest" in North America.

In addition to ensuring that growth in the American sports segments remained strong—hopefully helped by Thursday's launch of basketball star James Harden's new shoe—Mr. Rorsted said he wanted to continue leveraging Adidas's cooperation with rapper Kanye West and the positive stir around its urban lifestyle brand Originals.

To keep the current momentum strong, he planned to continue restricting the supply of certain shoe models, he said. He also wanted to make sure the different franchises at Adidas's lifestyle segment were strong enough to compete with each other, allowing for one shoe style to go down for a while without significantly impacting the business, he said.

Write to Sara Germano at sara.germano@wsj.com and Ellen Emmerentze Jervell at ellen.jervell@wsj.com

(END) Dow Jones Newswires

December 01, 2016 15:15 ET (20:15 GMT)