It's exceedingly rare to see a century-old company with a market value of more than $450 billion post-double-digit percentage sales growth. But that is exactly what Novo Nordisk (NVO 0.84%) did Thursday. The Danish drugmaker reported results for the nine-month period covering Jan. 1 through Sept. 30 ahead of the opening bell. In response, traders bid up the pharma giant's stock by 3.5% as of 2:10 p.m. ET Thursday, adding more than $15 billion to its market cap in the process.

A growth powerhouse

Thanks to the breakout success of its type 2 diabetes and weight loss drug semaglutide, Novo Nordisk generated a sizzling 29% year-over-year increase in sales (in Danish kroner) over the first nine months of 2023. Semaglutide is marketed as Ozempic and Rybelsus for type 2 diabetes and as Wegovy for weight loss.

Perhaps the best part for investors, though, is that this blistering growth probably won't slow down anytime soon. The company scored yet another major win for its flagship medication last month.

Specifically, the drugmaker halted an outcomes trial that had been ongoing for four years, evaluating semaglutide in type 2 diabetics with chronic kidney disease, after an interim analysis hit the pre-specified criteria for efficacy. The full data readout won't be available until 2024, but it looks like Novo Nordisk stands a good chance of adding another major indication to the drug's label.

Is Novo Nordisk stock still a buy?

Whether this stock is a good pick to add to your portfolio at this point all depends on your investing horizon. At current levels, Novo Nordisk's shares are a tad pricey at 15.4 times trailing 12-month sales. However, the drugmaker's stock may still be cheap for those willing to hold over the next five to 10 years. Semaglutide, after all, is forecast to become one of the best-selling drugs of all time by 2031.