Surprise Is the Only Signal That Matters

The CPI came in at 2.65% last month. Was that good or bad for stocks? The answer has nothing to do with 2.65%. It has everything to do with what the market expected—and the surprise was modest enough to keep investors calm.

This is the central insight that separates sophisticated macro investors from headline-chasers: the level of any economic indicator matters far less than its deviation from expectations. A 3% inflation reading that's 0.5% below consensus is bullish. A 2% reading that's 0.5% above consensus is bearish. The number itself is almost irrelevant.

To test this, I calculated inflation "surprise" as the difference between actual CPI and the 5-year breakeven inflation rate (the market's best guess at future inflation). Then I measured how the S&P 500 performed over the following six months. The results are striking.

The surprise-return relationship

I bucketed 131 months of data (2015-2025) by surprise magnitude. The pattern is nonlinear—and counterintuitive at first glance.

The best forward returns come not from "in line" readings, but from mild upside surprises. When inflation runs slightly hotter than expected (but not too hot), the market interprets it as economic strength without policy alarm. The economy is doing better than feared, but not so well that the Fed panics.

Why large surprises destroy returns

Large upside surprises (inflation running more than 1.5 percentage points above expectations) produced the worst forward returns: -0.59% over six months with only a 29% win rate. This happened most dramatically in 2021-2022, when inflation persistently exceeded expectations by 3-5 percentage points.

The 2021-2022 period stands out as an outlier. Inflation surprised to the upside by 3-6 percentage points for eighteen consecutive months. The S&P 500 fell 25% from peak to trough. But the damage wasn't caused by inflation itself—it was caused by the Fed's belated response to persistently missed expectations.

Contrast this with 2024-2025, where surprises have been modest (+0.3 to +1.0pp). Markets have rallied despite inflation remaining above 2%. Why? Because the surprise component has been manageable.

The expectation anchoring problem

There's a subtlety here that matters for positioning. Expectations themselves adjust over time. If inflation surprises to the upside three months in a row, the market revises its expectations upward. The fourth month might show the same inflation level but register as "in line" because expectations caught up.

This is why 2021 was so painful. Expectations kept adjusting upward, but actual inflation kept exceeding even the revised expectations. The surprise component never disappeared. The market couldn't find stable footing.

Current positioning

As of December 2025, the inflation surprise stands at +0.41 percentage points (2.65% actual vs 2.24% expected). This falls squarely in the "mild upside surprise" bucket—historically the most favorable for forward returns.

The implication is straightforward: the current inflation environment is not a headwind for equities. The market has already priced in expectations, and actual readings are coming in only slightly above those expectations. This is the Goldilocks zone for stocks.

Stock implications by surprise regime

Different stocks react differently to surprise regimes. During large upside surprises, commodity producers and energy stocks outperform as they benefit from the underlying price pressures. During mild surprises or in-line readings, growth stocks dominate because rate expectations remain stable.

The current mild upside surprise regime favors financials and industrials—sectors that benefit from a strong economy without excessive rate volatility. Utilities and REITs, which suffer when rate expectations rise, are less attractive.

Financials: Current Regime Winners

Large-cap banks and financial services companies thrive when inflation runs slightly hot. They benefit from steeper yield curves, stronger loan demand, and a resilient economy. Here are the largest financials positioned for the current surprise regime:

Industrials: Economic Strength Beneficiaries

Industrial companies outperform when the economy runs hotter than expected. Mild inflation surprises signal strong demand without Fed panic. These names benefit from the current regime:

Rate-Sensitive Names: Underweight in Current Regime

Utilities and REITs suffer when inflation surprises to the upside because rate expectations rise. These high-dividend sectors trade like long-duration bonds—avoid in the current environment: