28-Day Cetes Tick Up, Reigniting the Debate Over “Real Returns” in Mexico

The upward adjustment in the 28-day rate confirms a market focused on inflation and the path of interest rates in Mexico.

Yields on Treasury Certificates (Cetes) showed mixed moves in the latest government securities auction, with the 28-day tenor moving higher, according to results published by the Bank of Mexico (Banxico). With inflation still above target and bouts of external volatility, short-term instruments are once again drawing the attention of savers and investors.

In the auction, 28-day Cetes rose by 0.05 percentage points versus the previous auction, landing at 6.54%. By contrast, the 91-day yield fell 0.18 points to 6.49%. The 182-day and one-year tenors came in at 6.74% and 7.17%, respectively, with slight declines from the prior event. This setup points to a curve shaped by specific adjustments rather than a uniform shift in the government’s funding costs.

The move comes as annual headline inflation stood at 4.45% in April, still well above Banxico’s target (3% +/- one percentage point). From a macro perspective, as long as inflation remains above the target range, the market typically demands additional compensation—even if marginal—at maturities perceived as more sensitive to price data and central bank communication.

For retail savers, Cetes continue to serve as a low-risk, relatively liquid investment benchmark, especially compared with more volatile alternatives. Their face value is 10 pesos and they are purchased at a discount: you pay less today and receive the face value at maturity, with the difference representing the return.

Inflation, Rates, and Calculating the Real Return

Beyond the “nominal” rate announced at auction, the key question for measuring purchasing power is how much you earn in real terms. A simplified way to estimate it is to subtract annual inflation from the instrument’s annualized yield. With a 28-day Cete at 6.54% and annual inflation at 4.45%, the estimated real return would be around 2.09 percentage points. While this calculation doesn’t replace a more precise measure (for example, incorporating forward inflation expectations), it helps explain why these instruments remain attractive when inflation cools but hasn’t fully returned to target.

In practice, the “real return” also depends on an investor’s time horizon: someone who rolls over every 28 days faces the risk that rates fall if the monetary cycle enters an easing phase; by contrast, someone choosing longer tenors is trying to lock in a rate for longer, but takes on the opportunity cost of being “locked in” if rates rise. In Mexico, that tradeoff matters because the disinflation cycle hasn’t been linear and because supply shocks—energy, food, and the exchange rate—can reshape the outlook over relatively short periods.

From a public finance perspective, changes at the short end of the curve matter as well: a higher refinancing rate can increase debt service costs as the government rolls over short-term maturities. Still, the net impact depends on the debt portfolio mix, the amortization schedule, and access to markets, as well as the liability-management strategy.

Looking ahead, Cetes performance will remain tied to readings on core inflation, Banxico’s stance, and perceptions of global risk. Episodes of external stress often boost demand for liquid, shorter-duration instruments, while clear signs of inflation converging to target could show up in a downward rate trajectory—with direct implications for those renewing short-term investments.

In sum, the uptick in the 28-day Cete confirms a watchful market: as long as inflation doesn’t return sustainably to the target range, investors will continue weighing protection of real returns and the flexibility offered by shorter tenors.