Zero-day options traders increasingly bet against big S&P 500 swings

Bloomberg reports that zero-day options traders have increasingly bet on a calm S&P 500 even as other investors brace for swings. Citing an analysis by UBS strategist Kieran Diamond, Bloomberg says traders have shifted toward buying calls and selling puts when the market falls, then doing the opposite during rallies—a pattern UBS says further suppresses index swings. MarketWatch, also citing UBS analysts, reports that growing options trading has gained influence over how S&P 500 prices are set.