The Winds of Change Are Blowing: Why MBS Now?

With recent cooling in economic growth, an uptick in unemployment, inflation moderating back to the Federal Reserve’s (Fed) 2% target, and expectations for rate cuts, we believe the winds are shifting in the U.S. fixed income market.

In our view, investors may need to adjust their sails to harness the shift in a way that could benefit their portfolios. As they chart a course in this new environment of lower economic growth and declining interest rates, we believe investors should consider an allocation to agency mortgage-backed securities (MBS).

Following are five reasons why we believe MBS are poised for relative outperformance.

  1. Catching the interest rate downwind

As shown in Exhibit 1, the Fed’s benchmark interest rate is expected to be cut by more than 2% over the next 12 months.

If short-term rates do decline as expected and the yield curve steepens (i.e., yields on short-duration bonds fall more than yields on long-duration bonds), we believe securities such as agency MBS that have exposure to all parts of the yield curve (short, medium, and long) have a high probability of capturing the positive effects of interest rate cuts.

Additionally, we believe MBS can complement the shorter-duration and floating-rate exposures many investors have allocated to in recent years. Floating-rate bonds continue to offer attractive yields on the back of interest rates that are still at multi-decade highs. We believe investors should continue to lean into short-duration yields, while adding exposure to MBS to potentially catch the downwind of declining rates.

exhibit 1

  1. Prepayment risk at historically low levels

Agency MBS are backed by the U.S. government and therefore carry a negligible amount of credit risk. Prepayment risk is the primary fundamental risk for agency MBS, however. Homeowners may pay off or refinance their mortgage at any point, which would negate the future income on that mortgage for an investor.

Generally, refinancing increases when interest rates fall, as homeowners attempt to switch to lower-rate mortgages. These prepayments result in the duration of MBS falling when interest rates decline, a concept known as negative convexity. As a result, MBS may not fully realize the price appreciation from declining interest rates compared to a bond whose duration rises (positive convexity) when rates fall. To compensate investors for this risk, MBS pay an additional yield, or spread, above the yield on a comparable U.S. Treasury. (The Bloomberg U.S. MBS Index has on average in 2024 paid a 0.47% spread over U.S. Treasuries.)

While prepayments are an ever-present risk, the MBS market presently finds itself in a unique situation where prepayment risk is at historically low levels. As shown in Exhibit 2, due to an extremely low rate environment in 2020 and 2021, 76% of existing mortgages were originated at an interest rate below 5%, while the current mortgage rate hovers above 6.5%. To create a financial incentive for most homeowners to refinance, the mortgage rate would need to drop well below 5%, the likelihood of which we think is slim within the next 12 months.

In addition to the current environment offering no financial incentive to refinance, it actually disincentivizes many homeowners from moving (also leading to lower prepayments), as they would be giving up their “cheap” mortgage for a more expensive one.

In a nutshell, we do not expect prepayments to materially increase as rates come down, resulting in the duration of MBS remaining more stable and allowing the sector to better harness the positive effects of falling rates.

exhibit 2