When the price of Mortgage Backed Securities (MBS) on the above chart above goes up mortgage rates come down. When the price goes down mortgage rates go up.
The chart above was created at 9:48 am et. On this chart you will see that bonds are close to a 2 year high. This is due to money moving out of stocks and into bonds. This volatility was created by the UK's decision to move out of the European Union (Brexit).
Below is the news when it happened and market reaction. All of the times below are Eastern Standard Time
9:42 am et - Indexes Below