Shares of Opko Health (NASDAQ: OPK) had another poor showing in November, with its stock shedding a whopping 19.5% of its value last month, according to data from S&P Global Market Intelligence. Opko's shares have now lost a stunning 43.4% of their value so far this year. Opko's chronic woes stem mainly from the poor commercial performance of its two core value drivers: prostate cancer test 4K Score and the chronic kidney disease drug Rayaldee.