Below is a chart and excerpt from today's Early Look written by Macro analyst Ryan Ricci.  

PPI did come out yesterday as a declaration, but your CPI-PPI divergence is a 3.1 Z Score (compressing for the first time in 5 months). The last time we had a Z Score like this was Feb 1973 - Nov 1974, the SPY only saw a -48% draw down in that time.

CHART OF THE DAY: CPI-PPI Divergence Similarity Going Back 1973 - 982