Remember inflation? It's back, and it's bringing a familiar, unpleasant surprise. The March Consumer Price Index (CPI) report, scheduled for release at 8:30 a.m. ET on Friday, will deliver the first hard data on how the war in Iran has reshaped the inflation outlook. Wall Street expects the answer to be, well, ugly.

Consensus calls for headline CPI to jump 0.9% in March on a monthly basis. That would mark the steepest monthly rise since June 2022. To put that in perspective, since the post-2009 recovery, there have been only five months where the monthly CPI reading hit 0.9% or higher—all of them between October 2021 and June 2022, at the peak of the post-pandemic inflation surge. March 2026 is likely to join that short, painful list.

Why the sudden spike? It's almost entirely a function of one variable: energy prices, which have surged more than 10% in a single month. The conflict in Iran disrupted oil flows through the Strait of Hormuz, and that shock is about to show up in your CPI report. And it doesn't stop there—energy costs feed into transportation, manufacturing, and utility costs, which reinforce price rises across virtually all markets. Conflict-induced supply shocks have a way of rippling through the whole economy.

March Inflation Preview: What Wall Street Expects

President Donald Trump, during a January speech in Davos, Switzerland, claimed that "inflation has been defeated." Friday's report might tell a different story.

Bank of America economists forecast a 0.91% month-over-month surge in headline CPI, driven by a 10.6% jump in energy prices. Core CPI—which strips out food and energy to capture underlying price pressures—is expected to come in at a cooler 0.26% for the month, implying a 2.7% year-over-year rate.

"This month is likely too early to see significant signs of the Iran war in the core data. That said, we will be watching airfares and delivery services to see if there are any early signs of higher oil prices seeping through to the broader basket," said Bank of America economist Stephen Juneau in a preview note.

Goldman Sachs similarly forecasts the monthly jump at 0.87%, which will push the annual rate from 2.4% in February to 3.3% in March, in line with consensus estimates.

The Oil Shock Transmission To Inflation

Here's how an oil shock works its way into consumer prices. There are two channels.

The direct channel—gasoline, utilities, jet fuel—hits CPI energy in the month the price move occurs. That's what Friday's report will capture. The indirect channel takes longer: higher trucking and logistics costs, elevated manufacturing input prices, and airline surcharges that pass through to leisure and business travelers over subsequent months.

Goldman's rules of thumb are explicit on the math: a sustained 10% increase in oil prices boosts headline CPI by 25–30 basis points and core CPI by just 4 basis points. So Friday's print is largely a story about energy, not embedded inflation. The real test will come in April and May data, when Goldman and Bank of America expect tariff effects and oil passthrough to begin surfacing in goods categories and services.

The Historical Playbook: When CPI Jumps, These Stocks Tumble

In the post-2009 era, headline CPI has risen 0.9% or more month-over-month on only five occasions—all of them during the peak inflation cycle of late 2021 and mid-2022:

• November 10, 2021 — October 2021 CPI (0.9% m/m): first shock reading confirming inflation was not transitory
• December 10, 2021 — November 2021 CPI (0.9% m/m): second consecutive hot print, forcing Fed pivot narrative
• April 12, 2022 — March 2022 CPI (1.1% m/m): first inflation reading after the Russian invasion of Ukraine
• June 10, 2022 — May 2022 CPI (0.9% m/m): confirmation of the energy shock
• July 13, 2022 — June 2022 CPI (1.2% m/m): final surge before inflation peaked

Each release triggered an identifiable market rotation. Using market data filtered to companies with market caps above $50 billion, the consistent pattern across those five events was sharp selling in high-multiple growth, financials and cyclicals.

November 10, 2021 — October CPI Release: Worst Performers

December 10, 2021 — November CPI Release: Worst Performers

April 12, 2022 — March CPI Release: Worst Performers

June 10, 2022 — May CPI Release: Worst Performers

July 13, 2022 — June CPI Release: Worst Performers

The pattern holds across all five events: high-valuation growth names—crypto exchanges, software platforms, e-commerce—bore the steepest losses on the first two November and December 2021 prints, when the inflation surprise was freshest. By mid-2022, the damage had rotated into financials and travel names, as the market repriced both rate expectations and economic slowdown risk.

Notably, Blackstone appeared on three of the five worst-performing lists, a signal of how persistently higher-for-longer rates are compressing alternative asset managers.

What Investors Should Watch Friday

The divergence between a hot headline print and a relatively contained core reading creates a tactical ambiguity. Bank of America will be watching for early signs of oil pass-through in airfares and delivery services—the categories most sensitive to jet fuel and diesel costs. Goldman Sachs flags tariff-exposed goods such as recreation, household furnishings and personal care as secondary pressure points where inflation could surprise to the upside independently of oil.

The open question heading into Friday is not whether March CPI will be hot—it will be. The real unknown is whether the data confirms a geopolitically-driven one-month spike that fades as oil stabilizes, or whether it marks the first data point in a new inflation regime where the Iran war has durably repriced the cost of everything that moves. But markets may not have that luxury to wait.