How Fed bond sales reach a homebuyer’s rate
A fixed-rate mortgage often does not stay on a lender’s books. The lender can bundle many mortgages into a mortgage-backed security (MBS)—a bond whose investors receive the borrowers’ principal and interest payments. That gives lenders a way to replenish funds and make more loans.
When the Federal Reserve buys MBS, it becomes a large source of demand. If it stops buying or sells bonds it already holds, private investors must take up more of the supply. To attract them, MBS prices may have to fall. Because a bond’s promised payments are worth less when bought at a lower price, its yield—the return investors expect—rises.
Why a bond yield affects mortgage offers
Investors compare MBS with other bonds, including U.S. Treasury securities. They generally want extra return for the risks and complications of mortgage bonds: borrowers can refinance or repay early, changing how long investors receive payments. If MBS yields rise relative to other funding benchmarks, lenders typically need to offer borrowers higher rates to sell new loans at a price investors will accept.
The pass-through is not automatic or one-for-one. Mortgage rates also reflect Treasury yields, lender costs and competition, and the additional return investors demand for holding MBS. A Fed sale can add upward pressure, but other forces can offset it.
The borrower feels the market before the Fed
Mortgage quotes can adjust as investors anticipate a change in Fed demand, rather than waiting for bonds to be sold. And the effect can reach beyond the securities the Fed holds: when those bonds become less attractive, investors may seek higher returns across the wider mortgage market. The practical link is a chain—from a smaller official buyer, to changed bond prices and yields, to the rate a lender can offer on a new loan.
