What: Celldex Therapeutics (NASDAQ:CLDX) was up as much as 14% today on no fresh news.

So what: This is the second straight day that the biotech has experienced a move in the double digits. Momentum is clearly on Celldex's side.

CLDX Price data by YCharts

Zoom out that chart, though, and you can see that investors may just be latching onto any good news, as the stock has dropped quite a bit over the last few months without anything for investors to get excited about. Between the second- and third-quarter earnings announcements, Celldex issued just one press release about a presentation at the Leerink Partners Immuno-Oncology Roundtable -- a typical investor presentation without any new data.

CLDX data by YCharts

Investors are likely moving back into Celldex Therapeutics because early next year the biotech will take a second interim look at the ACT IV study testing Rintega in newly diagnosed glioblastoma. If the data is positive enough, the trial would be stopped early, and Celldex could apply for regulatory approval.

Now what: Until a biotech is selling a drug, the only way for the company to increase its value is to present new data that makes its pipeline drugs more likely to be approved and used by doctors. Some investors move in and out of stocks based on when the companies are going to release data, thereby avoiding owning shares of a company that isn't likely to go up in the short term.

Long-term investors can just ignore the gyrations and wait for the data, saving trading costs and the stress of trying to time the moves in and out.

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.