S&P 500has plenty of bullish momentum heading into the end of the year, and the latest jobs report from the Labor Department highlighted just how strongly the economy is rebounding now that COVID-19 vaccinations are widespread. Yet economic recessions always catch investors off guard, so Brad McMillan, Chief Investment Officer for Commonwealth Financial Network, regularly monitors a handful of recession risk factors to gauge U.S. economic risk. Yield Curve & Valuation The first risk factor McMillan is watching is the yield curve between 10-year Treasuries and three-month Treasuries. That yield curve steepened in October for the third consecutive month and has headed back toward historical norms, but McMillan said rising yields can also pose a threat to equity valuations. The second risk factor is market valuations. The S&P 500’s cyclically adjusted Shiller P/E or price-to-earnings ratio has trended higher for four consecutive months and is at its highest level since …