Arena Pharmaceuticals (ARNA) is falling after two research firms wrote in notes to investors earlier today that the company's anti-obesity drug, Belviq, is unlikely to be approved in Europe. The E.U.'s regulator last month refused to approve a competing drug, VIVUS' (VVUS) Qsiva, Needham analyst Alan Carr noted. Furthermore, the regulatory environment in Europe tends to be less favorable to drug companies, added Carr, who maintained a Hold rating on Arena. Similarly, Oppenheimer analyst Boris Peaker believes that the E.U. will probably not approve Arena's drug. If the drug is approved, reimbursement rates are likely to be low, added Peaker, who maintained a Perform rating on Arena. In late afternoon trading, Arena fell 21c, or 2.5%, to $8.10.