Goldman Sachs analyst Robert Koort upgraded Westlake Chemical to Buy from Neutral and raised his price target for the shares to $84 from $81. The stock's 49% decline over the past year has created an opportunity to gain exposure to two commodity cycles that are bottoming, ethylene and chloralkali, Koort tells investors in a research note. He believes Westlake will see margin growth and valuation improvement as investors gain comfort with the establishment of an ethylene "super trough" in the second half of 2019. Further, the company has even greater exposure to the chloralkali "cyclical rewind" as the fall of caustic soda prices approaches a bottom again, says Koort.