Why This Top-Ranked IBD 50 Stock Just Tumbled On Its Earnings

IBD 50 stock Exelixis (EXEL) toppled early Thursday on a mixed second-quarter report, as sales of its bread-and-butter cancer drug, cabozantinib, lagged expectations. The biotech company sells cabozantinib under the brand names Cabometyx and Cometriq. The former — a treatment for kidney, liver and thyroid cancers as well as neuroendocrine tumors — brought in $570.6 million in quarterly sales. Cometriq,…