Both stocks and bonds have a historical negative correlation. Why did both crash so hard on 9Sep2016?
Are you sure about the historical negative correlation?

Money just leaving the marketplace?

I believe that the correlation you are talking about is NOT on day or minute level. One day up/down doesn't say anything.Both stocks and bonds have a historical negative correlation. Why did both crash so hard on 9Sep2016?
You can think about it as about robots doing trades based on momentum or whatever. One day really doesn't mean that the correlation is gone. It's similar with stocks and gold correlation. You can see the correlation on 10 years chart, not one day chart.Ten years from now, you won't even remember Friday. In my time trading, I remember the first trade in stocks, first trade in Commodities, First spread...ect. We often remember the bad things first before the good times, stay long enough, you see repeating and only differences is names people assign to it, it all becomes blurb.
You trade your Trading Plan, whether it make sense or not, let newspaper report so they can sell papers.

- But Fridays market routing was significant, current, and news worthy.
- What happened 10 years ago is history and distant memory.
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