not to be pedantic, but my understanding is their value dropped because the treasury is selling higher interest bonds. Why would anyone buy a low interest bond at face value when for the same-price purchase a high interest bond?
It's not just that. A bond's price is simply the sum of its discounted future cash flows. i.e. the coupon value divided by (1+) the interest rate. When interest rates rise, the price goes down.
The Fed will accept treasuries as collateral for face value loans to banks for 1 year as part of the announcement. The losers here will be bank shareholders (of underwater banks) because they will need to dilute themselves to make up the difference when the loan gets called unless they can find other ways to make money in the meantime.
