Here is a stab at it.
The news today about the upcoming release of the Johnson-Crapo bill had within it the idea that the GSEs will be wound down and dissolved. This is not significant news to an informed long term investor since this was already promoted by the Corker-Warner bill that dried up in committee.
This means the new bill is no better in providing a lasting impact than the former one it copies and modifies. It will not pass.
However, the news was used as "catalyst" by MMs and large traders to bring the share price down in order to reposition themselves (average down) and/or realize gains and for those MMs, large traders and retail to cover million of shares in outstanding open short positions.
Traders and some investors took the decline in share price to be actually related to the news. The news appeared and the share price went up not down for awhile. Then the fear that the share price would drop began to set in when the rise turned around and headed downward. The stage was set and then, as if on cue, the price went steadily, slowly downward. Fear of a dumping set in.
A commonly done manipulation by those with the wherewithal to do it.
This was the directed downward pressure and it was scaled and executed algorithmically beginning at 1:15 pm EST to 2:45 pm. Take a look at the one minute chart to see the smooth transition downward. From that end time, the price rose algorithmically upward until 4:18 pm EST where it reversed and then at the end reversed again.
Added to this directed pressure was fear of loss of unrealized gains. This supplied the shares to buyers on the way down who were trying to guess the bottom caused by smaller traders focused in the day, short term and intermediate terms as well as those who consider themselves long term investors but who are indeterminate about holding if the share price goes south.
On the way back up shares were bought to reestablish open positions and for day traders buying and then selling for specific gains. Trading shares ran out and settled back to the closing price after a small boost at the end.
