Here's some good news for a company that could use a bit of a boost. The U.S. Food and Drug Administration said on Friday that BioMarin Pharmaceutical Inc. (BMRN) can now offer its PKU drug, Palynziq, to younger patients. Specifically, adolescents aged 12 and older who have phenylketonuria, or PKU.

For those who don't have a medical dictionary handy, PKU is a rare inherited disorder. It causes an amino acid called phenylalanine to build up in the body, which can lead to serious neurological problems if not managed. The standard treatment has been a very strict, lifelong diet. Palynziq works differently—it's an enzyme substitution therapy designed to help break down that amino acid.

This expanded approval makes Palynziq the only enzyme therapy approved for managing PKU in this pediatric age group. The FDA's decision is based on results from a Phase 3 study called PEGASUS. In that trial, patients on Palynziq showed a statistically significant reduction in their blood phenylalanine levels after 72 weeks compared to those who were just on the restrictive diet.

It's not just a U.S. story, either. BioMarin is also pursuing a similar label expansion with the European Medicines Agency, which could open up the treatment for teens in the EU as well.

Now, you might think a regulatory win like this would give a stock a nice pop. But the market can be a fickle thing. BioMarin shares were actually down about 3.9% in premarket trading on Monday, hovering around $59.30.

Looking at the stock's technical picture adds some context to that move. The shares are trading below their key short- and medium-term moving averages, suggesting some weakness. Over the past year, the stock is down roughly 19% and is sitting closer to its 52-week lows than its highs. Some momentum indicators are sending mixed signals: the Relative Strength Index is neutral, but the Moving Average Convergence Divergence is hinting at bearish pressure. Key technical levels to watch are resistance around $73.50 and support near $50.00.

Despite the recent stock performance and mixed technicals, Wall Street analysts haven't lost their enthusiasm. The consensus rating on BioMarin remains a Buy, with an average price target of $88.80—that's a hefty premium to where it's trading now. Just last week, analysts were busy updating their models: Canaccord Genuity raised its target to $104 and kept a Buy rating, Bernstein bumped its target to $94 with an Outperform rating, and Guggenheim, while maintaining a Buy, slightly lowered its target to $86.

So, what do you have? A company that just successfully expanded the market for one of its important drugs to a new group of patients. The stock, however, is acting like it got bad news, caught in a broader challenging environment for biotech. And the people who get paid to analyze these companies for a living still see a lot of upside. It's a classic setup where the fundamental story and the stock price story are telling two different tales, at least for the moment.