Shares of Celldex Therapeutics, Inc. (NASDAQ: CLDX), a clinical-stage biotech developing novel cancer therapies, fell 21.4% during midday trading on Monday despite a complete lack of news. As of 2:57 p.m. EDT, the stock was down 11.9%, possibly because investors were concerned the company had nothing worth mentioning to present this month's biggest oncology conference. Although it's hardly significant, investors can't be pleased with Celldex Therapeutics occupying a booth at the European Society of Medical Oncology's annual meeting over the weekend without sharing any new data.