S&P 500 sector weightings are important to monitor. Over the years when weightings have gotten extremely lopsided for one or two sectors, it hasn’t ended well. Below is a table showing S&P 500 sector weightings from the mid-1990s through 2012. In the early 1990s before the Dot Com bubble, the US economy was much more evenly weighted between manufacturing sectors and service sectors. Sector weightings were bunched together between 6% and 14% across the board. In 1990, Tech was tied for the smallest sector of the market at 6.3%, while Industrials was the largest at 14.7%. The spread between the largest and smallest sectors back then was just over 8 percentage points.

The Dot Com bubble completely blew up the balanced economy, and looking back you can clearly see how lopsided things had become. Once the Tech bubble burst, it was the Financial sector that began its charge towards dominance. The Financial sector’s sole purpose is to service the economy, so in our view you never want to see the Financial sector make up the largest portion of the economy. That was the case from 2002 to 2007, though, and we all know how that ended.

Unfortunately we’ve begun to see sector weightings get extremely out of whack again as 2017 comes to an end.