What happened

Week to date, shares of Planet Fitness (PLNT 1.05%) were down 16%, according to data provided by S&P Global Market Intelligence. The gym operator reported worse-than-expected earnings results for the first quarter.

The company demonstrated growth in the right metrics that point to solid footing in its growth trajectory. The market's focus on the miss, relative to expectations, might give long-term investors a good buying opportunity.

So what

Stock prices can often swing wildly after earnings reports if revenue and earnings per share don't meet the Street's estimates. When the stock is trading at a valuation that implies high growth expectations, an earnings miss can torpedo the stock in the near term.  

The stock's price-to-earnings ratio of 31, based on this year's earnings estimate, is higher than the average stock's multiple of 23, but that valuation seems warranted, given the company's strong recovery over the last few years. Planet Fitness delivered robust revenue and adjusted earnings growth of 19% and 28% year over year, respectively, which would seem to justify the high valuation. The company has been on a steady growth trajectory since recovering from the gym closures during the pandemic. 

Planet Fitness ended the quarter with over 18 million members. The company experienced the highest quarterly member additions since the first quarter of 2020. It shows the priority people place on their health and fitness, even during a rough economic patch with high inflation.

Now what

Overall, the company's double-digit growth only validates the long-term outlook for the business. Growing profits will allow management to reinvest in technology and a dedicated international team to support its growth initiatives. In fact, Chief Operating Officer Edward Hymes mentioned that the company is "just getting started" on its international expansion plans. 

I look at the post-earnings sell-off as a buying opportunity.