You listen to the talking heads and they have come up with at least 59,999.999 reasons why the bust down today. The spending bill...McMasters being kicked out...tariffs...blah blah blah.
This thing was baked in back at the lower red arrow and for sure at the upper red arrow. If you want to look for a "why" look back at those dates not what happened today as a cause.
The most likely reason it went down...if you have to have a reason...it went up to far to fast.