But there is a non-statistical basis for concern: an ominous parallel with the financial environment that prevailed in the weeks leading up to the October 1987 stock-market crash. On that day — Black Monday — the Dow Jones Industrial Average dropped 22.6% in a single session.

The yield on the 10-year hit a 52-week high of 4.896% on January 13, a week before Trump's second inauguration, and traded as low as 3.860% on April 4 before spiking to 4.607% on May 21, then settling at 4.431% on July 18.