A recent decline in U.S. Treasury yields has sparked interest in understanding the role of convexity buying by mortgage portfolio managers and insurance companies. This purchasing activity aims to counterbalance the effects of mortgage refinancing amid lower interest rates, potentially amplifying the yield reduction observed over recent weeks due to economic growth concerns. Analysts suggest that convexity buying began early this month as yields dropped to their lowest since late October, following a significant rise earlier in February. The 10-year yield, influencing borrowing costs for homes, cars, and businesses, has seen minimal movement since hitting its bottom around 4.10% on March 4, after a substantial decline from February.
In response to falling rates, investors in mortgage-backed securities (MBS) adjust hedges on mortgage holdings to rebalance their portfolios. This involves buying either Treasuries or Treasury futures, along with interest rate swaps, where they receive fixed rates while paying floating ones. To hedge against negative MBS convexity, investors also purchase receivers in the swaptions market, which has shown a skew towards more receivers anticipating further rate declines. While active MBS hedgers have decreased over time, convexity hedging remains evident through tightening spreads between 10-year interest rate swaps and Treasury yields, impacting swap rates due to increased demand for fixed-rate payments.
The Mechanics of Convexity Buying
Convexity buying refers to the strategic purchases made by mortgage portfolio managers and insurers to manage the impact of changing interest rates on their portfolios. As rates decrease, these entities must recalibrate their hedges to maintain portfolio balance, often resulting in amplified movements within Treasury yields. This process is crucial for offsetting the effects of mortgage refinancing, which can significantly alter the duration and yield characteristics of their investments. By engaging in convexity buying, these stakeholders aim to preserve the stability and performance of their financial instruments amidst fluctuating market conditions.
When interest rates fall, borrowers tend to refinance or prepay their loans, shortening the average life of mortgage bonds and reducing their yield. This phenomenon, known as negative convexity, leaves investors with shorter-duration portfolios than desired. To address this imbalance, mortgage players including originators, servicers, and MBS investors typically shift their hedges by purchasing Treasuries, Treasury futures, or entering into interest rate swaps. These actions help them align their portfolio durations with benchmarks, ensuring consistent returns despite varying interest rate environments. For instance, an investor might choose to receive a fixed rate while paying a floating one in a swap agreement, effectively protecting against further rate decreases. Additionally, some participants opt for receivers in the swaptions market, paying premiums for the right to receive fixed rates on swaps, thus preparing for potential future rate fluctuations.
Market Indicators and Implications of Convexity Hedging
Signs of convexity hedging are apparent in various market indicators, particularly in the behavior of swap spreads and implied volatilities. Recently, the spread between 10-year interest rate swaps and Treasury yields tightened considerably, reflecting heightened demand for fixed-rate payments during periods of convexity buying. This tightening results in more negative differentials between the two assets, directly impacting swap rates. Furthermore, short-term implied volatility on longer-dated swaptions, such as those tied to 10-year and 30-year swap rates, has risen, indicating elevated uncertainty and expectations of underlying convexity needs in the market.
The tightening of U.S. 10-year swap spreads, dropping to minus 44 bps from minus 38.30 bps since mid-February, exemplifies the influence of convexity hedging activities. Meanwhile, the increase in implied volatilities of three-month options on 10-year swap rates to a four-month high suggests a volatile landscape driven by policy uncertainties and trade-related factors under the current administration. Despite fewer active MBS hedgers today compared to previous years, the impact of convexity moves remains significant. Market experts highlight that while short-dated option volatility has been influenced by policy uncertainties, expectations of convexity requirements likely contribute to elevated levels in longer tenors. Overall, these dynamics underscore the complex interplay between convexity buying and broader financial market trends, shaping the trajectory of U.S. Treasury yields and influencing investment strategies across sectors.
