There was heavy volume on the DJIA today, but not really on the Nasdaq and low volume on the QQQ. On Yahoo Finance they say it is because of MRK, and that is probably true to some extent, but it doesn't tell me what to expect from the markets in the future. Whatever happens tomorrow, they will say it is because of the presidential debate.
But the heavy volume is important to note when watching the charts.
Large volume like this on a down or unchanged day looks weak to me. Next week we should see either last weeks highs being broken on the upside or this weeks lows on the downside. My guess is that this volume confirms that last weeks highs are set as lower highs in the down trend since the beginning of the year.

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