One of the keys to long-term success is to find an "edge" in the markets and exploit it repeatedly. What we find when we look carefully is that often some of the most consistent market edges "hide in plain sight." This piece highlights a monthly phenomenon in the stock market that fits the bill.; The past 200 days in the S&P 500 have been among the index's most consistent ever. But there have been 18 other stretches that show a very high positive correlation, so we look at these analogs and see some short-term weakness among many of them.

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