It’s been a long time since the S&P 500 has had a perfect week. By perfect, we mean five consecutive days stretching from Monday through Friday with the index setting a new record high each day. The last one was recorded in 1998, according to Howard Silverblatt, senior index analyst for S&P Dow Jones Indices.

Are we about to break that dry spell? Today, the S&P 500 closed at a fresh record high for the fourth consecutive day, something that hasn’t happened since November 2014. Up 11 points, or 0.5%, the benchmark ended at...