Dubbed the " September Effect," this phenomenon sees the S&P 500 averaging a negative 0.8% return since 1926, the only month with a consistent negative average over nearly a century. Theories abound as to why: from portfolio rebalancing by institutional investors to tax-loss harvesting and post-vacation market jitters.
There are lots of ways to measure home prices. Repeat-sales indexes like the S&P Cotality Case Shiller are very effective at tracking changes in the value of homes, but are very slow and lag the actual market. Market-based measures like the Altos price or the Altos pending price are immediate and best to answer What do homes cost today? These measures move together generally but can have subtle differences in timing and noise.