Shares of Aimmune Therapeutics Inc. jumped in their market debut on Thursday, while Planet Fitness’ stock declined. Discount gym chain Planet Fitness (PLNT) shares didn’t run out of the gate on its first day of trading, but there are plenty of reasons to get excited about the company’s prospects. Amplify’s shares were priced well above the expected pricing range, while Sunrun’s IPO was priced at the mid-point.

At today’s low, Planet Fitness’ valuation is approximately $1.36 billion. “If the company fails to deliver, the stock price can suffer as it has done with Twitter”, said Jay Ritter, IPO expert and professor of finance at the University of Florida. Amplify’s 10% fall marked a rare setback for a high- profile IPO that had been priced above its range and likely signaled a warning to big-name consumer brands preparing to go public.

The company, which caters mainly to first-time or occasional gym users, says its cheapest package is $10 per month, compared with the industry average of $46.

Fitbit (NYSE:FIT), a maker of wearable fitness tracking devices, reported quarterly earnings above analyst views late Wednesday in its first quarter as a public company.

In its prospectus, Planet Fitness said it expected to open more than 1,000 new stores in the next seven years.

The Newington, N.H.-based fitness chain, known for its no-frills atmosphere, and TSG Consumer Partners sold 13.5 million shares for $16 apiece, according to data compiled by Bloomberg, after offering them for $14 to $16. Its revenue rose 33% to $279.8 million a year ago.

Planet Fitness, the gym partner for NBC’s popular TV show ” The Biggest Loser”, owns 58 fitness centres and franchises more than 950 in the United States, Canada and Puerto Rico.