What happened

With earnings season in full swing, biotechnology stocks were volatile today.

Apellis Pharmaceuticals' (APLS 2.39%) stock, for instance, dipped by as much as 8.5% in early-morning trading Monday before rallying in the afternoon session. Apellis' shares ultimately ended the day down by a far more modest 1.80%. By contrast, TG Therapeutics (TGTX 1.35%) shares climbed by 23.4% today on heavy volume, printing a fresh 52-week high in the process. Viking Therapeutics (VKTX 1.10%) also joined the bull parade today, with its stock first rising by 7% in the early portion of Monday's session before cooling off to finish up by approximately 3.8%.  

So what

What drove these hefty price swings in these three biotech stocks today? Apellis appears to have been negatively impacted by the $5.9 billion buyout of Iveric (ISEE) by Astellas Pharma (ALPMY -0.32%) over the weekend. Iveric currently has an experimental geographic atrophy (GA) drug known as avacincaptad pegol under review with the Food and Drug Administration (FDA). GA is an advanced form of age-related macular degeneration that frequently results in total vision loss over time.

If approved, avacincaptad pegol would be the first commercial rival to Apellis' FDA-approved GA medicine, Syfovre. Apellis shareholders apparently weren't thrilled with the rather modest premium (21% relative to the stock's closing price last Friday) Astellas paid to acquire Iveric and its experimental GA treatment. Apellis, after all, has repeatedly been rumored to be a top buyout candidate, thanks to Syfovre's sizable commercial potential. 

TG Therapeutics stock raced higher today in response to better-than-expected sales of its newly approved multiple sclerosis drug Briumvi. Wall Street's consensus estimate stood at approximately $4.4 million for the three-month period heading into Q1 earnings. Today, the biotech reported net Briumvi sales of $7.8 million for the first quarter of 2023. TG Therapeutics commenced Briumvi's U.S. launch on Jan. 26, following its approval by the FDA last December. 

Shares of Viking Therapeutics continued their recent upward trend today, thanks to the highly anticipated trial results for VK2809 in biopsy-confirmed nonalcoholic steatohepatitis (NASH). With the study's patient enrollment period now complete, the biotech expects to announce top-line data in the second quarter of the year.

NASH is a potential $30 billion-a-year drug market. That's a massive commercial opportunity for a company with a $2.2 billion market cap at the time of this writing.  

Now what

Are any of these biotech stocks a buy on these latest price swings? It depends on your comfort level with risk.

On the one hand, Apellis, TG Therapeutics, and Viking Therapeutics all sport assets that could attract a suitor sometime soon. What's more, these three biotech companies also have exceptional organic growth prospects over the course of the decade, although risks abound in each case. So these three biotech growth stocks are arguably best suited for aggressive investors with a healthy appetite for risk.