From Avondale Asset Management:
It’s been a long time now since the S&P 500 had a big change in a
 single day. You have to go back to November of 2011 to find the last 
day that the S&P 500 rose or fell by 3% in one day. Since 1950 there
 have been 200 trading days out of 16,202 in which the S&P changed 
by 3% or more, which implies that we get one 3% day for every 81 days.
The current streak has lasted 623 trading days, which is the 6th 
longest period without a big change in the last 65 years.  From the 
history, it looks like most past streaks either fell just short of the 
600 day range or pushed through to the 900 day area....MORE