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What: Shares of Celldex Therapeutics (NASDAQ:CLDX) are down 11% at 3:00 p.m. EST, apparently because today is a weekday that ends in "y."

So what: I kid, but only slightly.

Shares of the biotech have closed lower than the day before in the last seven straight trading days, but there hasn't been any new news during that time. In fact, the last time Celldex Therapeutics issued a press release was December 8, nearly two months ago. On that day, shares closed at $15.58, about twice what they are today.

But it wasn't that press release that sent the biotech's share prices lower. The release announced the start of a phase 1/2 clinical trial testing Celldex's varlilumab and Roche's atezolizumab, a trial investors have known was coming since the partnership with Roche was established last March -- arguably a neutral-to-positive event.

Instead, the decline seems to be coming from a lack of confidence in Celldex's lead compound, Rintega. With an interim peek at phase 3 trial testing Rintega in a brain cancer called glioblastoma multiforme expected soon, investors clearly don't think the interim look will be positive, or -- worse yet -- they think the trial might be stopped early because it's clear the drug isn't helping patients.

Now what: A decline this large in the face of a lack of new information is certainly weird. It's possible that the results have somehow leaked out, so some investors know the interim look won't be positive. The other possibility is that investors are just taking risk off the table -- the biotech indexes have fallen substantially over this time -- so the decline has more to do with not wanting to hold through a binary event than the belief that Celldex's binary event is going to come up negative.

If the latter is true, then the risk-reward proposition is better now than before the slide began.

Brian Orelli has no position in any stocks mentioned. The Motley Fool recommends Celldex Therapeutics. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.