Markov Regime Switching Risk-On/Risk-Off Model for Treasuries

 

Data from FRED as of 30 Sep 2025.

In this post we explain the use of Markov Regimes Switching Risk-On/Risk-Off Model (MRS) for Treasuries.  The characteristics of Debt securities as an asset class are very different from Equities- the issuers and holders of Debt securities, the way they are traded, the role of liquidity, the importance of persistence and duration in yields- all make risk-on/risk-of models useful. Markov-type models with their wide scope for modifications e.g. Hidden Markov, Semi Hidden Markov; and enhancements are very well suited to this task. In this post we will show the current state of risk for different tenors of Treasuries.  We also have a supplementary paragraph to show why Money Market Funds are low -risk.

Methodology

We model regime shifts in Treasuries using price-based, weekly slope signals rather than raw yields.  Using prices (and their derived yield differences) ensures direct linkage to investor gains and losses, while avoiding the unit and scaling inconsistencies that can arise when mixing yield levels across tenors and sampling frequencies. We aggregate to weekly (Fri) observations for stability and to minimize microstructure artifacts, holiday gaps, and false flips that daily data can induce in regime identification. Instead of the level of a single tenor’s yield, we use the slope (e.g., 30Y–10Y, 10Y–2Y, 6M–3M) because slopes encapsulate the market’s relative expectations across horizons—term premium, policy path, and growth/inflation narratives—yielding a more robust, stationary-like signal that is less regime-unstable than raw levels. This is particularly important when comparing money-market vs. long-duration segments, where absolute yield moves have very different volatilities and are not directly comparable.

Think of the Treasury market as a curve rather than isolated points.

For example, when the front end (2-year) moves one way and the long end (30-year) moves the other, the shape of the curve is telling us something about growth-inflation expectations that a single-tenor model can miss. By fitting each tenor separately, we ignore that cross-tenor “slope” signal, so the model may latch on to one stable state and hardly budge.  Bringing slope data into the model gives it richer information. Therefore, we chart the 30y-10y, 10y-2y and 6m-3m risk probabilities.

We estimate regime probabilities via a robust two-state hidden Markov model, which we refer to as a t-like Sticky HMM (t-SHMM), with some resemblance to Student t distributions that can accommodate heavy tails and skewness . Practically, we achieve t-style robustness with light Winsorization of Z-scored weekly slopes and enforce persistence (“stickiness”) through high self-transition priors; this guards against outliers and spurious whipsaws while preserving responsiveness to genuine regime shifts. The lower-variance state is interpreted as Risk-On for slopes, and we report the smoothed probability of that state as our p_mean. Thresholds (e.g., 55–65%) and short persistence filters ( 3 weeks) define actionable windows while keeping the signal intuitive and visually consistent across tenors. Note: The charts use a 3-week persistence overlay (shaded) above a 65% threshold to highlight sustained risk-on periods, and mitigate flip-flops.

To initiate the reader on the topic, we first show a chart of the yields of long, medium and short-term Treasuries (T) below for you to visualize how the 2y,10y and 30y are behaving.

The next few self-explanatory charts show the current risk level of different tenors of T. 




Insights?
The charts are explanatory. The main takeaway is that long term Ts (30y-10y) are currently risk-off, medium term Ts (10y-2y) are currently risk-on, and 6m-3m Ts are at lowest level of risk-off. But in the case of 6m-3m (which are money market funds (MMF)) as can be seen, the cycles of risk-on/risk-off are very regular and they also always touch the maximum and minimum levels of risk-on/risk-off before they reverse. The regularity of cycles as shown in our MRS means that MMFs can buy/sell on the way up/down

Modified Duration and Money Market Funds Risk
The Modified Duration (MD) -a metric used by debt securities issuers/buyers/sellers that measures price sensitivity to interest rate changes, indicating the expected percentage change in a bond's price for a 1% shift in interest rates. Calculated by dividing Macaulay Duration by (1 + (Yield-to-Maturity / Number of Coupon Payments per Year)), it is a critical tool in fixed-income risk management to gauge how much a Treasury's price will fluctuate with interest rate movements. A higher modified duration signifies greater price sensitivity and thus higher risk in a changing interest rate environment. In the table below, you can see that the difference in MD between short-term, medium term, and long-term Treasuries is very significant.




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