Wall Street has spent days preparing for a Federal Reserve rate increase.

Now the bigger question is what happens after it.

The Federal Reserve is expected to raise its benchmark interest rate by 25 basis points on Wednesday, September 16, taking the target range from 3.50%-3.75% to 3.75%-4.00%. It would be the first U.S. rate increase since July 2023 and the first major policy test for Chair Kevin Warsh, who took over the Fed earlier this year.

The hike itself has become increasingly anticipated.

What remains uncertain is how Warsh describes the decision.

That distinction matters because financial markets have already priced in much of the expected move. Investors are looking beyond Wednesday's headline number and toward the Fed's updated economic projections, the voting pattern among policymakers and Warsh's press conference.

In other words, Wall Street may be preparing for a rate hike.

But it is really trading the words that come afterward.

The policy shift became increasingly likely after August inflation data showed renewed pressure.

Core consumer prices rose 0.3% in August, above the 0.2% increase economists had expected. That came alongside rising energy prices, with crude oil pushing above $100 a barrel as geopolitical tensions disrupted energy infrastructure and shipping routes.

The change in expectations has been dramatic.

A Reuters poll of more than 100 economists found that a majority now expected a September hike and at least one additional increase by the end of March. Goldman Sachs and JPMorgan also shifted their forecasts toward additional tightening after the latest inflation data.

That explains why a 25-basis-point increase no longer looks like a surprise.

Markets have had time to prepare.

The real uncertainty lies further down the road.

That is the question investors are trying to answer.

The Fed could present the increase as a limited adjustment designed to prevent inflation from becoming entrenched.

Or it could signal that additional rate increases are likely if price pressures remain elevated.

Those two interpretations could produce very different market reactions.

A more hawkish message could push Treasury yields and the dollar higher as traders price additional tightening.

A more cautious message could produce the opposite reaction, especially because markets have already adjusted to the expected September increase.

Reuters noted that analysts increasingly believe Warsh's communication could matter more than the 25-basis-point move itself.

This is especially relevant because Warsh has been described as favoring less extensive forward guidance than his predecessor, Jerome Powell. That could make the press conference unusually important for financial markets trying to determine the Fed's next step.

The Fed's decision is arriving against a backdrop of unusually high long-term borrowing costs.

The 10-year Treasury yield has recently moved above 5%, reaching levels not seen since 2007. On Wednesday, it remained close to that threshold as investors awaited the Fed decision.

That presents the central bank with a complicated problem.

The Fed controls the short-term policy rate.

It does not directly control the 10-year Treasury yield.

Long-term yields reflect inflation expectations, government borrowing, economic growth and investor demand for Treasury securities.

If the Fed raises rates but investors remain concerned about inflation and the supply of government debt, long-term yields could remain high.

That could tighten financial conditions even more than the central bank intends.

Energy prices have become a major part of the inflation story.

Brent crude has climbed toward $108 a barrel amid escalating conflict in the Middle East and disruptions to major energy routes. Wednesday's oil price had eased somewhat from the previous session, but remained elevated.

That matters because an oil shock creates an uncomfortable policy dilemma.

Higher rates cannot produce more oil.

They cannot repair damaged pipelines.

They cannot reopen shipping lanes.

Yet if expensive energy begins affecting transportation, services and inflation expectations more broadly, the Fed may have to respond.

This is why Warsh cannot simply focus on the latest headline inflation reading.

He has to determine whether today's energy shock is temporary or whether it could become embedded in the wider economy.

Warsh is also operating under intense political scrutiny.

President Donald Trump has repeatedly pushed for lower interest rates, while financial markets have increasingly priced in a hike.

That creates a difficult communications environment for the new Fed chair.

The central bank's credibility depends partly on convincing investors that its decisions are driven by economic conditions rather than political demands.

At the same time, monetary policy affects borrowing costs, mortgages, business investment and economic activity — issues with direct political consequences.

The tension is therefore unavoidable.

A rate hike would demonstrate that inflation remains a priority.

But Warsh will need to explain why higher borrowing costs are appropriate even as policymakers also monitor economic growth and employment.

Investors will be watching more than the policy statement.

The Fed's updated economic projections and “dot plot” will provide clues about where policymakers expect rates to go next.

Suppose the median projections show rates remaining relatively contained.

Markets could interpret the September increase as a limited adjustment.

But if the projections shift materially higher, investors could begin pricing a more sustained tightening cycle.

That would put additional pressure on bonds and potentially on highly valued stocks.

The distinction may sound technical.

It is not.

It determines the cost of money for millions of households and businesses.

The relationship between Fed rate hikes and stocks is not as simple as “higher rates equal falling stocks.”

Historical analysis cited in recent market coverage shows that the S&P 500 has often struggled during the first several months after the beginning of a rate-hiking cycle. Data covering six hiking cycles since 1994 showed average negative returns in the first four months, while performance tended to improve over longer periods.

That does not mean stocks must fall after Wednesday's expected move.

Markets can react differently depending on why rates are rising.

If rates increase because economic growth is strong and recession risk is limited, equities can behave differently than when hikes occur alongside a severe economic downturn.

That is an important distinction.

The Fed does not raise rates in a vacuum.

Markets care about the reason.

Technology companies could be particularly sensitive to higher long-term yields because many of their valuations depend on expectations for future earnings growth.

If investors can earn around 5% from Treasury securities, they may demand stronger growth from companies whose valuations already assume years of rapid expansion.

That is one reason the recent bond selloff has coincided with pressure on parts of the technology sector.

At the same time, strong earnings can offset some of the impact.

The market is therefore entering a period in which both valuation and corporate fundamentals matter.

The U.S. dollar is another market to watch.

A more hawkish Warsh could reinforce expectations for higher U.S. interest rates, potentially supporting the dollar.

A softer message could reduce those expectations.

The currency reaction could then feed back into commodities, emerging markets and global liquidity.

For investors outside the United States, a stronger dollar can make dollar-denominated debt and commodities more expensive.

The ideal outcome for policymakers may be relatively boring.

A predictable 25-basis-point increase.

A clear explanation of why inflation remains a concern.

No dramatic commitment to a long series of additional hikes.

And a message that leaves the Fed room to respond to incoming data.

But financial markets rarely remain quiet when the stakes are this high.

If Warsh sounds significantly more hawkish than expected, yields could rise.

If he sounds much more cautious, the dollar could weaken and financial conditions could ease.

Either response could affect stocks, bonds, crypto and commodities within minutes.

The Federal Reserve may deliver a 25-basis-point hike that markets have largely anticipated.

But the real test begins when Warsh starts speaking.

Does he describe the move as a one-time adjustment?

Does he signal that more hikes are coming?

Does the Fed's dot plot validate the bond market's concern about persistent inflation?

Or does the central bank leave the door open to a pause?

Those answers could matter far more than the first 25 basis points.

For Wall Street, the Fed's decision is not simply about the cost of money today.

It is about what the central bank believes the cost of money needs to be tomorrow.

And for the new Fed chair, that may be the first decision.

The harder one will be convincing the market that he knows where the path leads.