PORTLAND, United States — Nike Inc. shares fell to their lowest price in more than a year after Bank of America Corp. downgraded the company, saying it's lost ground in a critical area: innovation.

Competitors such as Adidas AG and Under Armour Inc. are developing new products at a faster clip, making it harder for Nike to keep them at bay, according to analyst Robert Ohmes. He cut his Nike rating to the equivalent of a sell — becoming the first analyst to do so since last year, according to data compiled by Bloomberg.

“Nike is at least 12 months away from returning to market-share gains,” said Ohmes, who also trimmed his 12-month stock-price target to $46 from $55. The analyst previously had a neutral rating on Nike.

Sentiment has been shifting negative on Nike this year, with investors growing increasingly concerned that its growth momentum is fading. Adidas, meanwhile, has made gains with retro sneakers and casual apparel. And Under Armour, once a football brand, has pushed into basketball and is now expanding overseas.

Ohmes downgraded Nike after meeting with Asian suppliers and competitors, who said Nike’s innovation engine is not the advantage it once was. During the Olympics, Nike did not unveil a new major product platform — a break from its past strategy.

Shares Slide

The shares fell as much as 3.6 percent to $50.15, the lowest price since August of last year. Even before the latest dip, the stock was down 17 percent this year. Nike had been thriving in the years since the recession, with the stock averaging annual gains of 26 percent since 2008.

The threat to Nike is real, but it is probably only a matter of time before new products help the company rebound, said Chen Grazutis, an analyst at Bloomberg Intelligence.

“Nike has dominated the US athletic footwear market for so long that this dual threat from Adidas and Under Armour is really something people have a hard time evaluating,” he said. “Yet, a closer look at the the competitive pressures brings up the possibility these might be temporary in nature.”

By Sarah Very and Matt Townsend; editors: Bill Austin, Nick Turner and Kevin Orland.