S&P 500 single stock valuations have the tightest spread in 25 years, with eight out of ten sectors below their long-term averages, according to a note from Goldman Sachs Group, Inc. (NYSE:GS). “The distribution of S&P 500 stock P/E multiples has been tightening since mid-2012 and is well below the average of 55% since 1990,” says the note. The current dispersion of price/earnings is 1.5 standard deviations below the 30 year average, and the only sector that is significantly above its 30 year average is Financials where rising interest rates and other effects are benefiting some players and hurting others,…