Altimmune (ALT -3.62%) had some encouraging news to share with the world as the trading week drew near a close on Thursday. The biotech announced that it will soon ascend to an important, specialized stock index; investors greeted this news by trading the company's stock up by more than 3% on the day. This provided quite a marked contrast to the general trend for stocks, as the S&P 500 index dipped marginally across the session.

Inclusion in an industry index

Before market open, Altimmune divulged that it is being added to the Nasdaq Biotechnology Index (NBI). The move will be effective prior to the trading kickoff next Monday, Dec. 23.

Although the index is large and sprawling, with over 600 component stocks, it nevertheless conveys a measure of prestige to those titles. Also, at a stroke, it raises Altimmune's profile and makes the biotech eligible for inclusion in one of the many index funds currently popular among the public.

In the press release trumpeting the development, Altimmune quoted its CEO Vipin Garg as saying that its inclusion on the NBI "is an important recognition to conclude what has been a year of major progress for the company."

Could weight loss mean financial gain for the company?

While there's a certain, inevitable measure of hype in Garg's statement, he isn't wrong. Altimmune has shot to prominence largely on the back of its investigational drug pemvidutide, a GLP-1 treatment for obesity.

It has tested quite well in clinical trials so far and could be quite the outperformer in this hot segment if ultimately approved by regulators. That's because, compared to rival treatments, it appears to limit the reduction of muscle mass in patients.