Moody Street in the heart of downtown Waltham has long been known for its eclectic collection of small, locally owned shops and dining spots. But the closing of three restaurants in the past month has highlighted the area’s heavy business turnover, and sparked concern among neighboring restaurants.

“It’s a scary thing,” said John Young, regional manager of Stadium Sports Bar and Grill, which opened on Moody Street in January. “I mean, we’re a small company too.”