 Shares of Bausch Health Companies Inc. BHC, -50.29 suffered a near-record plunge of 50.3 in volatile afternoon trading Thursday before a trading halt, after Bloomberg reported that some of the drug and medical device makers patent claims tied to its treatment for irritable bowel syndrome, Xifaxan, were invalid. The stock was halted for volatility three times in morning trading before being halted for news since 10:33 a.m. 