What happened

Shares of BioNTech (NASDAQ:BNTX) were jumping 4.7% higher as of 2:52 p.m. EDT on Tuesday after rising as much as 10.9% earlier in the day. The gain appears to be the result of continued momentum from Monday's news. BioNTech and Pfizer (NYSE:PFE) announced positive preliminary results from early-stage testing of COVID-19 vaccine candidate BNT162b1 yesterday. The partners also announced a deal to supply 30 million doses of their COVID-19 vaccine candidate to the United Kingdom pending success in clinical testing and regulatory approval.

BioNTech is taking advantage of this momentum. The German biotech announced Tuesday morning that it plans to offer 5 million American Depositary Shares (ADS) in a public stock offering.

Gloved hands holding bottles labeled coronavirus vaccine.

Image source: Getty Images.

So what

Normally, secondary stock offerings cause share prices to fall rather than move higher. The dilution resulting from the offerings reduces the value of existing shares. The fact that this didn't happen for BioNTech underscores just how much potential investors see for the company's COVID-19 vaccine candidates.

Experts are looking for three key things with experimental COVID-19 vaccines: neutralizing antibody production, T-cell response, and an acceptable safety profile. BioNTech and Pfizer delivered on all three fronts with the results they announced yesterday for BNT162b1, the most advanced of several COVID-19 vaccine candidates the two companies are evaluating.

Those were only early-stage results in a small number of participants, though. It remains to be seen whether the BNT162 program produces positive results in larger, late-stage studies.

Now what

The good news is that investors shouldn't have to wait very long to find out how safe and effective BioNTech's COVID-19 vaccine candidate will be in late-stage testing. BioNTech and Pfizer hope to begin a phase 2b/3 clinical trial including up to 30,000 participants later this month pending regulatory approval. The German biotech stock will almost certainly have an even bigger catalyst on the way if this study goes well.