How quiet is this record-setting stock market? By at least one measure, the S&P 500 index is on pace to register is lengthiest period of quiescence in more than two decades—and perhaps ever. The broad-market benchmark hasn’t experienced a decline of at least 3% since Nov. 7, 2016. That 237-day span registers as the second-longest period without a single-session drop of that magnitude since the 241 days from Jan. 26, 1995 to Jan. 9, 1996, according to Pension Partners’ Charles Bilello (see table below): via