A signal of a possible stock-market correction has flashed. - Stocks and oil face a volatile session for Thursday with investors in the thick of trying to navigate a worsening Iran conflict. Our call of the day from independent investment research provider Variant Perception says its tactical correction signal for the S&P 500 SPX has activated for the first time in nearly two years, as it warns of prolonged volatility for investors. Most Read from MarketWatch The last such signals were triggered in Ap ...