Lululemon will benefit from recent problems at its main competitors, according to a top Wall Street firm.

Bank of America Merrill Lynch raised its rating on Lululemon shares to buy from underperform on Monday, saying the company is taking sales away from Nike and Under Armour.

Lululemon is “gaining share from saturated competitors. We believe weakness in Nike and Under Armour North America apparel sales creates share gain opportunity for Lululemon,” analyst Rafe Jadrosich wrote in a note to clients Monday. “Nike and Under Armour have suffered from a lack of innovation, over-distribution in moderate channels, and heavy promotions.”

Lululemon has underperformed the market this year with its shares down 10.6 percent through Friday, compared with the S&P 500’s 8.3 percent return.

The analyst raised his price target for Lululemon to $70 from $49, representing 20 percent upside from Friday’s close.

Jadrosich said Lululemon’s recent products such as the Enlite bra, Nulux fabric and Wunder Under technology will drive sales growth in the future.

“Lululemon’s fabric and product innovation appears robust, in our view,” he wrote. “We believe lulu will increase its assortment of Jacquard (specialized knitted and dyed nylon yarn that allows designers to form unique textured patterns), which will carry higher average selling prices and is difficult to replicate.”

As a result, the analyst predicts the company’s same-store sale growth will increase to 5 percent in the July quarter from the negative 1 percent in the April quarter.

Shares of Lululemon rose 1 percent Monday morning after the upgrade.

— CNBC’s Michael Bloom contributed to this story.