The New York Stock Exchange had investors scratching their heads this week with the invocation of the little-known Rule 48.
The regulation was approved by the Securities and Exchange Commission in 2007 and is meant to calm a market opening in times of volatility. Though the exchange has lost more than 60 percent of its share of trading in the past 10 years, the NYSE still plays a role for investors and the financial media alike. So the sounding of an emergency bell before the Big Board lights up often presages a rough trading day.
Indeed, the S&P 500 has a median return of negative 1.2 percent on days that Rule 48 has been invoked, according to data from market research firm Kensho. Still, there are ways you can keep your head above water when the Rule 48 bell rings.