Indicate whether each of the following actions will Increase or Decrease a bond's yield to maturity and explain:

A bond is upgraded by the Standard & Poor's rating agency from BB to AA. A change in the bankruptcy code makes it more difficult for bondholders to receive payments in the event the firm declares bankruptcy. If a bond's price increases, then what should happen to that bonds yield? Investors are surprised to learn that a certain bond for AT&T is subordinated to another debt issue in that company. What should happen to the yield for the subordinated bonds once investors realize what has happened?