What happened

Although it had good news to report, Ocugen (OCGN 0.81%) nevertheless saw its stock decline by almost 6% on Monday. That news clearly wasn't good enough for investors, who were likely concerned about the company's lack of specifics.

So what

Ocugen announced that it had secured the rights to commercialize Covaxin, a coronavirus vaccine developed by its India-based partner Bharat Biotech, in Mexico. Ocugen already holds the North American commercial rights to the jab; this has been extended to the big country just south of the U.S.

Person about to receive a vaccine shot.

Image source: Getty Images.

Relative to other nations, Mexico has been fairly open about authorizing COVID vaccines -- 10 from various manufacturers have gotten the green light in the Latin-American country.

Among these are the popular mRNA-based shots Spikevax from American biotech Moderna and Comirnaty from Pfizer and BioNTech. Covaxin is a more traditional vaccine that utilizes an inactivated version of the coronavirus to produce its effects.

Covaxin currently holds emergency use authorization (EUA) in Mexico for patients aged 18 and older. An EUA application has been submitted to the country's healthcare regulator COFEPRIS for use in children between the ages of 2 and 18.

In its press release trumpeting the Mexico deal, Ocugen wrote that Covaxin "can be an ideal vaccination option for Mexico at this stage of the pandemic."

"It offers logistical advantages that could support vaccine access in hard-to-reach communities," the biotech added.

Now what

Yet Ocugen was mum on how much the rights expansion would cost (although it did say that this gives it "the same profit share structure as in the United States").

When such details aren't fully provided, investors tend to assume the worst -- in this case, perhaps they're worried that the American company might have paid a pretty penny to tap into that Mexican revenue stream.