Part 6 · Commodities and the global economy · Lesson 29
Oil is the blood of the economy
Crude oil runs through every corner of the economy, from factories and trucks to airplanes and home heating. When oil prices swing, inflation, interest rates and the fortunes of different sectors swing with them.
QToday's question
Why does news of war in the Middle East shake even my stock account?
In March 2026, as fears grew that an armed conflict in the Middle East could block crude oil shipments, WTI crude jumped more than 50% in a month. A few months later, US consumer price inflation rose into the 4% range, and interest rates and stock prices swung with it. In this lesson we follow the path by which the price of one barrel of oil reaches your grocery bill, interest rates, and sector report cards.
MAPLearning map for this lesson
We build it up in three steps. At the end of each step, a 'Quick check' lets you test your understanding before moving on.
In Lesson 3 you learned that goods whose supply reacts slowly see big price swings, and in Lesson 7 and Lesson 8 you learned about inflation and the difference between headline and core inflation. In Lesson 10 you saw that the 1970s oil shocks led to stagflation, and in Lesson 11 the scene where only the energy sector rose, +57.6%, in 2022. In Lesson 25 you also confirmed that a weak won raises airlines' fuel costs. This lesson ties these pieces together on a single thread called 'oil prices'.
- STEP 1 · Basic conceptsHow is the price of crude oil set?
You can tell apart , and explain why the price of crude oil, whose supply reacts slowly, swings so much.
- STEP 2 · Understanding the mechanicsThe path by which oil prices spread to inflation and interest rates
You can explain with a diagram how oil prices pass through gasoline and transport costs into headline inflation, and then through into core inflation and interest rates.
- STEP 3 · Real-world application50 years of oil prices, inflation and sectors
Using real data, you can check how closely oil prices and inflation moved together, and sort out why refiners, airlines and chemical companies react differently to oil price news.
STEP 1How is the price of crude oil set?
Oil news is full of unfamiliar words like 'barrel', 'WTI' and 'OPEC+'. Let's first sort out these terms and then look at why the price of crude oil swings so much.
An easy analogy · blood flowing through the body
In our bodies, blood starts at the heart and carries oxygen all the way to our fingertips and toes. When blood circulates well the whole body feels light, and when it gets thick or blocked, trouble appears here and there. Crude oil is the same. It is the fuel that moves trucks and ships, the raw material for plastics, fertilizer and fabrics, and what keeps us warm in winter. So when oil prices rise, costs rise all across the economy at once.
The three benchmark oil prices
The price of crude oil differs slightly by region of production and composition. In the market, the prices of a few reference grades of crude are used as . The price unit is dollars per barrel (about 159 liters).
The three prices generally move together, but gaps can open depending on shipping routes and regional conditions. In September 2026, risk rose around the Strait of Hormuz, the Middle East's oil shipping route, making Middle Eastern and European crude more expensive, and the gap between Brent and WTI widened to more than $10 per barrel. Korea imports almost all of its crude, and most of it comes from the Middle East, so it is especially sensitive to news from the region.
Why it swings so much on small shocks
As you learned in Lesson 3, prices are set by and . Crude oil is a good where both sides are 'sluggish'. Developing a new oil field takes years, so supply cannot be raised suddenly, and commuter cars and factory machines cannot simply stop when fuel gets more expensive, so demand does not fall easily either. So even a small supply disruption lets the people who 'have to buy anyway' bid prices up sharply, and conversely, if demand suddenly vanishes, prices can fall through the floor.
The loudest voice on the supply side is . It is a grouping in which Russia and others are added to OPEC, the club of oil-producing countries such as Saudi Arabia, and it influences oil prices by cutting output together (production cuts) or raising it (production increases). On top of that come US shale oil production, countries' crude inventories, and geopolitical risks such as war and sanctions.
According to a report from the US Commodity Futures Trading Commission (CFTC), the May-delivery WTI futures contract opened at $17.73 per barrel that day and closed at −$37.63. It was the first since trading began in 1983. With the tanks to hold crude full, oil had become a 'burden that had to be sold off'. It showed how extreme crude prices can get when demand does not just shrink a little but suddenly disappears.
Quick checkEven if global crude supply falls by just 2%, oil prices can jump more than 30%. Why is that?
STEP 2The path by which oil prices spread to inflation and interest rates
Now that you have seen how the price of crude is set, let's follow how that price spreads to our daily lives, to companies, and even to interest rates.
Oil ↑ → gasoline and transport costs ↑ → headline inflation ↑ → (if it spreads) core inflation ↑ → interest rates ↑ → stock multiples ↓
Oil prices spread through the economy along two paths: the first pushes inflation up directly, and the second spreads over time to other prices and wages. When the second path opens, the central bank moves and the multiple knob from Lesson 1 gets shaken.
See it in a picture: the path oil prices take
Change the WTI price with the slider, or press a button for an actual period. Compared with the starting point ($70 per barrel), it shows at a glance how gasoline prices, inflation and company earnings change. The numbers are a simple hypothetical model to illustrate the principle.
Oil 0% → gasoline 0% → inflation +0.0 pp
Simple hypothetical model: exchange rate fixed at KRW 1,400. Gasoline = crude cost × 1.15 + KRW 950 of taxes and distribution costs. Inflation contribution = oil price change × energy weight 7% × pass-through rate 50%. The hypothetical airline has KRW 2 trillion in fuel costs and KRW 1.2 trillion in operating profit at an oil price of $70 (no fare pass-through), and the hypothetical refiner holds 10 million barrels of crude inventory. It may differ from real companies and real inflation.
Press the 'May 2026' button. Oil is up 46% from the starting point, but gasoline rises only by close to 20%. A large part of the gasoline price is taxes and distribution costs unrelated to oil prices, which act as a cushion. Conversely, an airline, where fuel is a big share of costs, sees profit shrink sharply, while a refiner that has stockpiled crude sees the value of the same inventory rise, creating a paper profit ().
The first path: it pushes headline inflation up directly
Energy prices such as gasoline, diesel, heating oil, and electricity and gas bills are directly in the consumer price basket. So when oil prices rise, that month's move immediately. This is why, in Lesson 8, we look separately at , which excludes food and energy. Energy prices rise and fall sharply within a few months, so looking only at headline inflation makes it easy to miss the true trend in prices. In Korea too, petroleum product prices rose 22.2% in 2022, pushing consumer price inflation up to 5.1% (Lesson 7).
The second path: it spreads to other prices over time
Through transport and raw material costs, oil prices also pass into other prices with a lag. When trucking rates rise, delivery fees and food prices follow; when naphtha prices rise, prices of plastic containers and fabrics follow. This is the you saw in Lesson 9. Going further, if people believe that 'prices will keep rising', ask for bigger raises, and companies start adding those costs back into prices, inflation begins to feed itself. This is called a . In the 1970s oil shocks this path opened wide, inflation passed 10% and the economy sank, bringing (Lesson 10).
What central banks care about is precisely this second path. If an oil shock only lifts headline inflation briefly and passes, they can watch and wait, but if signs appear that it is spreading to core inflation and wages, they try to put out the fire by raising interest rates. When rates rise, the multiple knob from Lesson 1 turns down, and the oil shock becomes a burden on the whole stock market.
Common misconceptions
- "If oil prices rise, do stocks always fall?"
- What matters is 'why' oil prices rose. When oil rises because the world economy is strong and using a lot of oil, it can also be a sign that company sales are growing, so stocks may rise along with it. Conversely, oil prices that rise because supply is blocked, as in war or production cuts, only add costs and tend to weigh on the stock market.
- "Does the gasoline price move exactly like oil prices?"
- Gasoline prices include a large share of taxes such as fuel taxes and refining and distribution costs, so even if oil rises 40%, gasoline rises much less. There is also a lag of several weeks before international oil prices are reflected in domestic gas station prices.
- "If oil prices fall, are all sectors better off?"
- It is welcome news for airlines and transport, but refiners can take a loss as their inventory loses value (). And if the sharp drop in oil is due to a global recession, the whole market can weaken together.
Quick checkOil prices rose sharply and this month's headline inflation jumped. But core inflation is unchanged. Will the central bank raise rates right away?
STEP 350 years of oil prices, inflation and sectors
Now let's check with real data. Did inflation jump every time oil jumped? And who gained and who lost in the stock market at those times?
Overlaying oil prices and inflation
The chart below overlays the monthly WTI oil price (monthly average) and the US consumer price inflation rate (year over year) from 1970. Press a scene button below and that period is marked on the chart with an explanation.
WTI oil price vs US consumer price inflation (Jan 1970 – Aug 2026, monthly)
Hover or tap on the chart to see the two numbers for that month.
Source: St. Louis Fed FRED. Year-over-year growth is calculated from WTISPLC (WTI spot, monthly average) and CPIAUCNS (CPI, not seasonally adjusted). The October 2025 CPI was not published, so it is blank. The April 2020 figure of −$37.63 is from the US CFTC report (2020.11.23), and the WTI futures price of $102.48 on September 10, 2026 is from Yonhap News (2026.9.11). Checked 2026-10-05.
Most big waves of inflation had oil prices alongside them. During the two oil shocks of 1974 and 1980, US inflation soared to 12–15%, and the 9.1% inflation of June 2022, the highest in more than 40 years, also coincided with a monthly average oil price of $114.8. Calculating the correlation between the year-over-year change in WTI and the CPI inflation rate month by month for 1986–2026 gives 0.51 (Robin Invest calculation). That is a fairly clear relationship, but remember it is 0.51, not 1. Inflation is also driven by other forces such as wages, rents and demand, not only oil.
2008 and 2020 teach the opposite lesson. Both times oil prices crashed within a few months, and the cause was not oversupply but the world economy suddenly freezing. In those cases, falling oil was not 'good news' but a warning that demand was collapsing, and the stock market also fell sharply along with it.
In stocks: the same oil price, different sectors
Generally favorable when oil rises
Refiners · Energy · Drilling and equipment
Selling prices rise, and the value of crude inventories rises, creating inventory valuation gains. In 2022 the US energy sector (XLE) rose 57.6% while most other sectors fell (Lesson 11). However, a refiner's real strength depends on the , the gap between the gasoline price and the crude price.
Generally unfavorable when oil rises
Airlines · Shipping and transport · Chemicals
Fuel and raw material costs make up a large share of costs. Korean airlines buy fuel in dollars, so when oil prices and USD/KRW rise together, the burden doubles. Korean Air, which we saw in Lesson 25, said its fuel costs rose KRW 133.8 billion in Q2 2026 from the higher exchange rate alone.
| When you see news like this | Why oil rose | How to read it |
|---|---|---|
| "OPEC+ agrees to additional production cuts" | Supply cut | Favorable for refiners and energy, a burden for airlines and chemicals. If inflation worries grow, upward pressure on interest rates as well |
| "Oil surges on fears of a blockade of Middle East shipping routes" | Supply shock + anxiety | Along with oil, a preference for the dollar (Lesson 24) grows and a weak won tends to overlap. A double burden for sectors with large import costs |
| "Oil rises as crude demand grows with the economic recovery" | Demand increase | A sign that the economy is good. Cyclical sectors as a whole may rise together |
| "Oil plunges on recession fears" | Demand collapse | A cost saving for airlines, but a warning sign for the whole market. Joint declines are possible, as in 2008 and 2020 |
To see how oil prices are currently reflected in the environment scores of each sector, check the 'Oil up' row in the Macro Map's impact map, and for the flow from an oil surge to interest rates and sectors, see the 'Oil surge' scene in the causal chain.
This is not always so. A refiner can see profits fall even when oil rises if the refining margin is poor, and an airline can pass part of its costs on to customers through fares and fuel surcharges. How a sector reacts is determined not by oil alone but by why oil rose, the exchange rate, and demand together.
Quick checkNews says oil prices fell 30% in a month. Is that automatically good news for airline stocks?
✓What we learned today
- Crude oil is used throughout transport, production and heating, which is why it is called the 'lifeblood of the economy'. The benchmark prices are US WTI, European Brent, and Middle Eastern Dubai crude, which Korea imports in large volumes.
- Supply and demand for crude oil do not change easily in a short time, so prices move sharply even on a small supply disruption or a sudden demand collapse. On April 20, 2020, WTI futures closed at −$37.63, and in March 2026 they rose more than 50% in a single month.
- Oil prices move headline inflation directly through gasoline and transport costs, and if they spread to wages and other prices (a second-round effect), they push up core inflation and interest rates too. That is why central banks watch core inflation more closely.
- In monthly data for 1986–2026, the correlation between the year-over-year change in WTI and US CPI inflation was 0.51. Big waves of inflation, such as the June 2022 monthly average WTI of $114.8 with CPI at 9.1%, often had oil prices alongside them.
- When oil rises, refiners and energy companies tend to benefit from higher selling prices and inventory values, while airlines and transport with large fuel costs and chemicals with large raw material costs tend to suffer. However, the market-wide reaction differs by 'why' oil rose (strong demand or a supply shock).
When oil surges and news of war spreads, another asset gets attention too. It is gold, which pays not a penny of interest yet rises whenever people are anxious. In the next lesson, we will check how the gold price interlocks with real interest rates, the dollar, and central bank buying.
Quiz5-question quiz
Pick an answer and it's graded right away with an explanation.
Q1. What is the main reason crude oil prices swing sharply even on a small supply disruption?
Developing a new oil field takes years, and people cannot cut back on oil right away even when it gets more expensive. Both sides are sluggish, so prices move sharply even on a small supply disruption.
Q2. What is the most accurate direct reason WTI futures closed at −$37.63 on April 20, 2020?
Demand suddenly vanished and even the tanks to store crude filled up, so sellers flooded in trying to get rid of contracts obliging them to take delivery of oil, even if they had to pay to do so.
Q3. Oil rose 40%, but gasoline rose only around 20%. Why?
The gasoline price includes a large share of taxes such as fuel taxes and refining and distribution costs. Only the crude cost portion moves with oil prices, so in percentage terms it rises less.
Q4. What is the 'second-round effect' that central banks are especially wary of during an oil shock?
If an oil shock spreads through transport costs, wages and inflation expectations into core inflation, inflation starts to feed itself. This is what happened in the 1970s oil shocks.
Q5. Oil surged on fears of a blockade of Middle East shipping routes, and USD/KRW also rose. Which Korean sector is most likely to face the biggest burden?
Airlines buy fuel in dollars, so when oil prices and the exchange rate rise together, the fuel cost burden doubles. Refining and energy tend to be generally favorable when oil rises.
NextTerms · Next lesson · Related tools
The crude oil prices the market uses as references. The main ones are US WTI, North Sea Brent, and Middle Eastern Dubai crude, quoted in dollars per barrel (about 159 liters). The crude Korea imports is closest to Dubai.
OPEC+OPEC PlusA grouping in which other oil-producing countries such as Russia are added to the members of the Organization of the Petroleum Exporting Countries (OPEC), such as Saudi Arabia. By cutting output together (production cuts) or raising it (production increases), it has a large influence on oil prices.
Negative oil priceNegative oil priceThe event on April 20, 2020 when the May-delivery WTI futures contract closed at −$37.63 per barrel. When COVID-19 caused demand to collapse and storage space ran out, sellers piled in trying to get rid of contracts obliging them to take delivery of oil, even if they had to pay to do so.
Second-round effectsSecond-round effectsA phenomenon in which a price shock such as an oil shock spreads through wages, transport costs and inflation expectations to other prices and lifts core inflation as well. Central banks are especially wary of it when setting interest rates.
Refining marginRefining marginThe difference a refiner earns when it turns crude into gasoline, diesel and other products and sells them. It is the product price minus the crude price and operating costs, and it is the core of a refiner's profit.
Inventory valuation gain/lossInventory valuation gain/lossA paper gain or loss that arises when the value of crude and product inventories held changes with prices. When oil prices rise, refiners tend to book inventory valuation gains, and when they fall, losses.
CommoditiesCommoditiesBasic materials used in production, such as crude oil, natural gas, metals and grains. When their prices rise, they push up inflation and boost the profits of companies that produce and sell them.
SupplySupplyThe quantity that sellers are willing to sell at a given price. Normally, as the price rises, the quantity supplied increases (the law of supply).
DemandDemandThe quantity that people want to buy at a given price. Normally, as the price rises, the quantity demanded falls (the law of demand).
CPIConsumer Price IndexThe main price indicator showing changes in the prices of goods and services households buy. It is usually released as the rate of increase versus the same month a year earlier.
Core inflationCore inflationInflation excluding food and energy, whose prices swing widely. It is used to look at the underlying trend in prices.
Pass-throughPass-throughA company adding its higher costs to its selling prices and passing them on to consumers. Companies good at pass-through find it easier to protect their margins when costs rise.
StagflationStagflationA situation in which economic stagnation and rising prices (inflation) occur together.
Weak wonWeak wonA rise in USD/KRW, that is, a fall in the value of the won. It is generally favorable for exporters.
This is educational material and not investment solicitation. There is no guarantee that past relationships will repeat in the future.