US inflation figures released on September 11 revealed that core CPI rose 2.4% year-over-year in August, marking the lowest annual reading in five and a half years, though the monthly increase of 0.3% exceeded expectations and represented the largest gain in four months.

Following the data release, market analysts have largely concluded that the Federal Reserve will deliver its first rate hike in three years next week, with the more challenging question being what comes afterward. With few officials inside the Fed believing a single 25-basis-point increase will be sufficient to curb inflation, a decision to raise rates next week would signal that current rate levels are misaligned with policy needs, and correcting that misalignment will require more than a single step.

Investors now anticipate at least three cumulative rate increases by June of next year, up from the two previously expected, with the probability of a September hike surging to nearly 90% in futures markets.

Political Pressure Adds to the Fed's Challenges

The Fed also faces mounting political pressure. The president has previously voiced opposition to rate increases, expressing hope that the new Fed chair would deliver lower interest rates. The vice president recently welcomed the Fed's cooperation on rates, while the Treasury Secretary has argued that recent inflation stems from supply shocks and that the Fed should not tighten policy at this time.

Historical Precedent Shows Rareity of One-and-Done Hikes

Since the federal funds rate became the central tool for managing borrowing costs in the 1990s, there has been only one instance where the Fed raised rates a single time and then stopped — back in 1997. A former Fed vice chair now at Pimco stated plainly that if the Fed hikes next week, it certainly will not be a one-and-done situation, with more action to follow.

The Fed chair's own remarks have reinforced market expectations. He noted in July that he does not believe the Fed excels at "fine-tuning" the economy. Analysts point out that a chair skeptical of fine-tuning is unlikely to declare victory after a single 25-basis-point increase. A Fed governor echoed this logic last week, stating that a 25-basis-point hike at a single meeting will not be enough to bring inflation back to the 2% target.

A strategist at Piper Sandler and former senior Fed advisor emphasized that once you decide to tighten policy, you must push rates to a level where the restrictiveness becomes meaningfully impactful.

Inflation Data Becomes the Tipping Point

Prior to the latest figures, market opinion was divided on whether the September meeting would deliver a hike, but Friday's inflation data broke that equilibrium. Officials had predicted in June that monthly inflation would moderate in the second half of the year as tariff effects faded, and June and July data initially supported that view. However, the August data reversed the trend, with the key core consumer price gauge coming in stronger than expected, compounded by solid employment figures and rising oil prices driven by tensions in the Persian Gulf.

The August inflation data served as the tipping point, elevating market expectations for the September meeting from a single decision to the beginning of a broader policy path. The San Francisco Fed president recently described the Fed's choice as one between two economic scenarios: first, that shocks from the past two years gradually dissipate and current policy settings prove sufficient to bring inflation down; or second, that shocks accumulate and inflation spreads persistently, requiring adjustments far beyond 25 basis points. She noted that the first scenario remained her baseline forecast in early August, but the probabilities of both scenarios have since converged.

Chair's Stance on Forward Guidance Increases Market Pricing Risk

The Fed chair laid the groundwork for the "rates are at the wrong level" argument in his keynote speech at the Jackson Hole symposium last month. He has stated there is little evidence that current borrowing conditions are restraining economic activity, and that the June and July inflation improvements failed to convince him that the underlying trend has turned. This logic naturally raises the question of how much higher rates need to go.

Fed chairs have historically guided market expectations by explaining whether rate actions represent "recalibration," "preventive moves," or "risk management adjustments," without having to commit to a specific future path. However, the current chair has long harbored resistance to forward guidance, viewing it as constraining the central bank's policy flexibility.

A chief economist at BNY Investments and former director of the Fed's monetary affairs division warned that without guidance, a single rate hike becomes subject to amplification by market forces. He explained that without prior groundwork, policy actions face the risk of being overspeculated. Markets naturally interpret an initial hike as the start of a series, and without guidance, there is no way to suppress that expectation.

Hawkish Officials Look Ahead with Strong Conviction for Higher Rates

Officials favoring early action have strengthened their argument from a forward-looking perspective. The St. Louis Fed president stated in a recent speech that "earlier, more gradual, and smaller rate hikes are preferable to potentially later, more abrupt, and larger adjustments." He supported a hike at the July meeting as well.

This camp's case rests not only on the past three months of data but also on upcoming risks: the impact of war-related diesel price increases that have not yet fully transmitted through shipping networks; new tariffs set to take effect; large-scale AI infrastructure expansion stressing electricity and technology supply chains; and elevated stock prices continuing to support consumer demand.

That official made clear that over the next 12 to 18 months, the probability of inflation running significantly above the Fed's target now exceeds the probability of it returning to the 2% goal.

The Fed still holds one tool to shape expectations: the quarterly Summary of Economic Projections, which contains officials' anonymous judgments on the future rate path. At the June meeting, the chair declined to submit his dot-plot projection. A chief economist at Point72 Asset Management expects this round of projections to "send an unusually strong signal." If the chair explicitly frames the hike as "reversing part of last year's cuts," investors would interpret that as room for two to three additional hikes at most. However, he also noted this approach would conflict with the chair's longstanding opposition to providing such forward guidance.