Crude, CPI, and the Coin Flip That Isn‘t: What Moved Markets This Week | Week Ending 12 September 2026

The Week at a Glance

Wall Street walked into a holiday-shortened week already tired, and the week did not let up. US cash markets were shut Monday for Labor Day. From Tuesday’s open the S&P 500, Dow and Nasdaq lost four straight sessions — which is to say, every session until Friday — as oil pushed back through US$100 a barrel and Treasury yields tested the top of this cycle’s range. Friday’s August CPI print was the last major inflation reading before next week’s Federal Reserve decision. Headline came in as expected. Core did not. The tape still rallied, and not because the inflation story improved. Oil came off its highs, a September hike was treated as a known quantity rather than a shock, and Oracle’s results gave the AI-hardware complex permission to bid. All three major indices finished Friday higher. Not enough to erase the week’s losses. Enough to stop the bleeding.

The final scoreboard, Friday 4 September close to Friday 11 September close: the S&P 500 settled at 7,656.98, down 0.8% for the week. The Dow closed at 52,573.29, down 1.6% — its worst week since March. The Nasdaq finished at 26,333.04, down 0.7%. The small-cap Russell 2000, which has the least balance-sheet cushion against a higher-for-longer setting, fell 2.4% to 2,903.94.

Two storylines did almost all of the work this week: the price of oil, and the price of money. A third, quieter storyline played out on the other side of the Pacific. In the US book, energy equities absorbed a roughly 9% jump in crude and still held their ground. In the Australian book, the same oil shock and the same hawkish repricing hit miners and the currency instead.

1. The Iran Premium Isn’t Decaying — It’s Negotiating

The same US–Iran conflict in the Persian Gulf has been on the tape for months. This week it escalated again before it eased.

Renewed strikes and attacks on shipping through the Strait of Hormuz sent crude sharply higher through the middle of the week. WTI broke back above US$100 a barrel for the first time since May. Brent traded as high as roughly US$109 overnight Thursday into Friday. By Friday’s settlement WTI was near US$100.05 — last around US$99.99 — still up about 9.3% on the week and more than 20% over the past month. Brent settled around US$104.40–104.60, trimming an intraweek spike but still up roughly 9% for the week. US retail diesel printed a fresh record, above US$6 a gallon.

The relief, such as it was, came from diplomacy rather than de-escalation on the ground. Reporting through the week, including the Financial Times, said Gulf ministers are trying to work out a temporary arrangement with Iran to manage shipping through the Strait, with talks in Oman early next week. That headline was enough to take the war premium out of Friday’s price action. Nothing about the underlying conflict resolved. Markets priced a chance of a deal, not the fact of one.

The mechanical read-through matters more than the geopolitics for a portfolio. The Strait of Hormuz carries close to a fifth of the world’s seaborne oil. Every extra dollar on a barrel of crude is a direct input into the inflation print the Fed is about to react to — which is exactly what happened this week.

2. A Coin Flip No More

Last week Fed Governor Christopher Waller talked September hike odds down from the low-60s to roughly 50/50, conditional on August inflation data continuing to cool. He was not the only official leaving a hold on the table, and two softer summer prints had already done some of that work. This week the data did not cooperate.

Thursday’s Producer Price Index came in hotter than expected — up 0.4% month-on-month, with the annual rate accelerating to 5.4% from 4.8% — and knocked the wind out of a market that had been given permission to treat a hold as a live option. Friday’s Consumer Price Index landed on consensus for the headline, +0.4% month-on-month and +3.4% year-on-year, matching July’s annual pace. Core, stripped of food and energy, rose 0.3% against a 0.2% forecast. The one genuinely reassuring detail: core CPI on an annual basis eased a tenth, to 2.4% from 2.5%. CPI is the input the market trades; PCE is still the Fed’s reaction function. Neither measure is back at 2%.

Markets did not linger on the annual core nuance. Fed funds futures finished Friday around a 90% probability of a quarter-point hike at next week’s two-day FOMC meeting, lifting the funds rate from the 3.50%–3.75% range that has held all year. That would be the first increase in more than three years. It is a sharp reversal from the cutting-cycle narrative that dominated 2024–25, and from Waller’s own “give disinflation a chance” comments barely a week earlier. It is not the first hawkish turn of 2026 — the ECB and the RBA have already hiked this year — but it is the week the residual “cuts are still the base case” story finally left the US rate market.

The driver is not a strong economy overheating in the usual demand-side sense. It is an oil shock feeding back into the price data, at the same time consumers are telling survey-takers they expect more of the same. The University of Michigan’s preliminary September sentiment index printed 47.8 against estimates around 51. That is not a garden-variety miss. It is the second-lowest reading on record. One-year inflation expectations jumped to 4.6% from 4.0%.

The bond market had already moved. The 10-year Treasury yield tagged levels within a whisker of 5% mid-week — the top of this cycle’s range — and was still sitting in the mid-4.9s on Friday as oil pulled off its highs. Equities took their cues from the same tape: nine of eleven S&P sectors closed higher on Friday, led by technology, industrials and communication services, each up more than 1%. Healthcare and utilities, the two sectors with the least tolerance for a higher-for-longer discount rate, lagged.

It was not only the Fed. The European Central Bank hiked this week too, unanimously, lifting the deposit rate to 2.50%. President Christine Lagarde called it “a no brainer” against euro-area inflation running at 3.3% annually. The Bank of England and Bank of Japan both meet next week. The BoJ is expected to hike, and the yen has already rallied to a seven-month high in anticipation. For the first time in a long stretch, the world’s major central banks are tightening in near-unison rather than debating who cuts first.

Inside the index-level noise, the week was a dispersion market. Dell and Hewlett Packard Enterprise each jumped about 12% on Friday after Oracle’s results reassured investors that AI data-centre capex is still translating into hardware orders. Lumentum stayed bid on the same optical-and-AI infrastructure theme. On the other side, Cooper Companies was the ugly standout after a revenue miss, a guidance cut, and the decision to keep CooperSurgical rather than sell it — a mid-teens collapse that briefly made it the S&P 500’s worst name. Casey’s General Stores fell more than 16% even after an earnings beat, because inside same-store sales of 3.2% missed the 4.1% the market had wired in. When the index is only down slightly, that is where most of the actual risk — and the actual opportunity — was sitting.

3. Down Under: Banks Hold, Miners Don’t, and the RBA Starts Talking Like the Fed

While Wall Street argued with the Fed, the ASX 200 had its own rough week, and its own version of the same story.

The index touched 8,819.40 on Thursday and kept falling on Friday, closing at 8,741.20 — its lowest finish since early July. That is a 0.9% drop on the day and a 2.9% drop for the week, the second consecutive weekly decline and the steepest since March. The same forces were at work: oil approaching and briefly breaking through US$100 dented risk appetite, while a stronger-for-longer US rate outlook pulled global capital back toward the dollar. Locally the curve did the talking. The three-year government yield pushed through 5.0%; the 10-year printed around 5.37%.

The sector split was the week. Gold miners were Friday’s biggest losers after New York gold dropped about 2.3% on Thursday; Sydney was trading that tape, not Friday’s steadier US session. Spot gold finished the US week near US$4,366, down about 1.4% Friday-to-Friday. Evolution Mining, Northern Star and Genesis all finished lower. BHP dropped more than 4% as the broader resources complex sold off. The big four banks, by contrast, bucked the trend, rising on Friday and holding up on the week — a reminder that this week’s index-level pain was concentrated in miners and healthcare, not financials. At 4.35% after three RBA hikes this year, the banks are no longer fighting a cutting cycle. They are sitting inside one that may have another step left.

Healthcare added its own drag. CSL slipped around 2% in an already jumpy global healthcare tape. That is not a fresh guidance cut — the FY26 reset landed in May, on softer US immunoglobulin inventories, weaker albumin pricing in China, and generic competition in iron — but the de-rating has not been fully digested, and a risk-off week is when that residual hangs over the name.

The Reserve Bank added its own hawkish note to a week already full of them. Deputy Governor Andrew Hauser asked the question the board will actually take into this month’s meeting: have we done enough, or is more needed? Assistant Governor Sarah Hunter said the board has limited tolerance for inflation staying above the 2–3% target, and that if price pressures come in stronger than the forecast, rates may have to rise again. That is a materially different tone from where the RBA sat earlier in the easing-then-reversal cycle, and it landed alongside domestic data showing business confidence at a three-month low in August and consumer sentiment weakening further into September.

The Australian dollar wore the consequences. AUD/USD softened to around 0.717 by Friday, giving back the ground it held last week even as oil — usually an AUD-supportive tailwind as a commodity currency — kept climbing. This week a hawkish Fed repricing simply outweighed the commodity story. Iron ore, Australia’s largest single export, held up relatively well near US$98 a tonne after briefly printing just above US$100, still the strongest stretch since June.

That is the split a dual-listed book had to live with. In New York, energy as an equity sector absorbed the crude spike and finished the week roughly flat to slightly higher. In Sydney, the equities attached to the same commodity complex were the drawdown.

The Scorecard

US weekly performance is Friday 4 September close to Friday 11 September close. ASX week is Friday 4 September close to Friday 11 September close, Sydney time.

The Read

Two weeks running now, the same three ingredients have set the tape: oil, yields, and whatever the Fed is about to do about both. That is not a coincidence. It is the second half of 2026 compressed into a fortnight — a geopolitically driven energy shock feeding into a Federal Reserve that spent two years signalling cuts, spent the first part of 2026 arguing with a hold, and is now being priced to hike.

This is not a newly discovered problem. The Iran war has been in the price since February. What is new is the second leg of that shock arriving just as a two-month disinflation tease had given Waller, and the market, room to talk about giving cooling prices a chance. Hiking into a supply-side inflation spike is a different problem from the demand-side playbook most of this cycle was written for. Next week is the first live test of how much appetite the Fed actually has for that trade-off.

For a portfolio split across US and Australian holdings, the read is not “sell everything and wait for the Fed.” It is narrower than that. A hawkish surprise repriced everything with duration — long bonds, rate-sensitive growth stocks, and anything still trading on a “cuts are coming” multiple. US energy equities, and the oil strip itself, were the exception. Australian resources and the Aussie dollar were not. Watching the 10-year and the oil strip together, rather than the index headline alone, told you more about this week than either number did on its own. Watching which side of the Pacific the energy exposure sat on told you the rest.

Next Week

If the Fed does hike into an economy that is still absorbing an oil shock, the question this week only repriced gets an answer. The follow-through will show up first in the 10-year, then in the oil strip, and only after that in the index.

Data Sources:

• US Bureau of Labor Statistics, Consumer Price Index — August 2026, released 11 September 2026 (headline +0.4% m/m, +3.4% y/y; core +0.3% m/m; core y/y 2.4%)
• US Bureau of Labor Statistics, Producer Price Index — August 2026, released 10 September 2026 (+0.4% m/m; y/y 5.4%)
• University of Michigan Surveys of Consumers, preliminary September 2026 (sentiment 47.8; 1-year inflation expectations 4.6%)
• CME FedWatch / fed funds futures pricing, as of 11 September 2026 close (≈90% probability of a September hike)
• S&P Dow Jones Indices / Nasdaq / Russell weekly index closes, week ended 11 September 2026
• Associated Press, Reuters, MarketWatch market wraps, 8–11 September 2026 (index closes; WTI and Brent settlements; Strait of Hormuz reporting)
• Financial Times / Reuters, Hormuz shipping talks and Oman meeting reporting, 11 September 2026
• European Central Bank, September 2026 monetary policy decision and press conference
• S&P/ASX 200 (XJO) daily and weekly data, week ended 11 September 2026
• Reserve Bank of Australia, public remarks — Deputy Governor Andrew Hauser and Assistant Governor Sarah Hunter, 8 September 2026
• COMEX gold settlements and Trading Economics iron-ore spot, 11 September 2026
• AUD/USD Friday 11 September 2026 close

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