What happened

Shares of the large-cap biotech Moderna (MRNA 1.19%) are up by a healthy 10.2% as of 10:58 a.m. ET Thursday morning. The stock is up by double digits today in response to stronger than expected sales of its COVID-19 vaccine, Spikevax, in the fourth quarter of 2021.

Ahead of the opening bell, Moderna reported fourth-quarter 2021 revenue of $7.2 billion. Wall Street, by contrast, was expecting revenue of roughly $6.8 billion for the three-month period. 

Closeup image of the novel coronavirus.

Image source: Getty Images.

So what

Moderna's shares were down by a whopping 46% year to date prior to today's rally. The biotech stock was steadily trending lower due to concerns about the commercial longevity of its COVID-19 vaccine, along with Pfizer and BioNTech's rapidly growing share of the coronavirus vaccine market.

This Q4 earnings report, however, gives investors a few compelling reasons to believe that the market dynamics might be changing in favor of Moderna's Spikevax. Chief among these reasons, Moderna's vaccine clearly gained ground on Pfizer and BioNTech's rival product during the closing months of 2021 based on this sizable revenue beat. 

Now what

Is Moderna's stock a buy in the wake of this positive earnings report? It all depends on your view of the company's deep value proposition. Moderna now has a decent war chest consisting of cash and investments of $17.6 billion. What's more, the biotech announced a $3 billion share buyback program as part of today's earnings report. Lastly, Moderna has a whopping 44 clinical programs under development right now. So there is definitely a bull case to be made for this next-generation mRNA therapeutic and vaccine company.