---
title: "Aggregate Supply Shock — AP Macro Definition & Exam Guide"
description: "An aggregate supply shock is a sudden shift in SRAS that moves output and price level in opposite directions. Key to AD-AS graphing and cost-push inflation in Unit 3."
canonical: "https://fiveable.me/ap-macro/key-terms/aggregate-supply-shock"
type: "key-term"
subject: "AP Macroeconomics"
unit: "Unit 3"
---

# Aggregate Supply Shock — AP Macro Definition & Exam Guide

## Definition

An aggregate supply shock is a sudden, unexpected shift in short-run aggregate supply (SRAS). A negative shock cuts output and employment while raising the price level (cost-push inflation); a positive shock raises output and employment while lowering the price level (EK MOD-2.H.2).

## What It Is

An aggregate supply shock is a sudden, unexpected event that shifts the [short-run aggregate supply](/ap-macro/unit-3/long-run-self-adjustment/study-guide/VeYA6gFFsLYxu92do3Od "fv-autolink") (SRAS) curve. Think of a spike in oil prices, a natural disaster, or a surprise jump in [productivity](/ap-macro/key-terms/productivity "fv-autolink"). The defining feature is what happens to output and the price level. Unlike a demand shock, a supply shock pushes them in **opposite directions**. A negative supply shock (SRAS shifts left) means output and employment fall while the price level rises. That's the worst of both worlds, and it's exactly what the CED means by cost-push inflation (EK MOD-2.H.3). A positive supply shock (SRAS shifts right) raises output and employment while pulling the price level down.

Here's the part that connects Topic 3.6 to Topic 3.7. Supply shocks to SRAS are temporary in this model. In the [long run](/ap-macro/unit-3/long-run-aggregate-supply-lras/study-guide/ryR454U7pI6tFIKsreOV "fv-autolink"), with no government intervention, flexible wages and prices adjust and the economy slides back to full employment on the LRAS curve. Unemployment returns to its natural rate (EK MOD-2.I.1). So a shock to SRAS moves the economy in the short run, but it doesn't change potential output. Only a shift in LRAS itself changes the full-employment level of output, and that's economic growth, not a shock (EK MOD-2.I.2).

## Why It Matters

This term lives in [Unit 3](/ap-macro/unit-3 "fv-autolink") (National Income and Price Determination) and sits at the heart of two learning objectives. [AP Macro](/ap-macro "fv-autolink") 3.6.A asks you to explain, with graphs, how output, employment, and the price level respond to a supply shock in the short run. AP Macro 3.7.A asks the same question for the long run, where self-adjustment kicks in. Together, these are the core skill of Unit 3, which is drawing a correctly labeled AD-AS graph, shifting the right curve the right direction, and reading off what happens to real GDP and the price level. Supply shocks are also your gateway to stagflation, the one scenario where output falls and inflation rises at the same time. That matters again in Unit 5, because policymakers facing a negative supply shock have to choose between fighting inflation and fighting unemployment. They can't fix both with one tool.

## Connections

### Long-Run Self-Adjustment (Unit 3)

A supply shock is temporary in the AD-AS model. After a negative shock, high [unemployment](/ap-macro/key-terms/employment "fv-autolink") pushes wages down, which lowers production costs and shifts SRAS back to the right. The economy returns to full employment on its own, which is the whole point of Topic 3.7.

### [Recessionary Gap (Unit 3)](/ap-macro/key-terms/recessionary-gap)

A negative supply shock creates a [recessionary gap](/ap-macro/key-terms/recessionary-gap "fv-autolink"), since short-run output drops below full employment. But unlike a demand-driven gap, this one comes with a rising price level, so the usual 'recession means low inflation' intuition breaks.

### Supply shocks and the Phillips Curve (Units 3 and 5)

A negative supply shock shifts the short-run Phillips curve right, raising both inflation and unemployment at once. This is why supply shocks show up again in [Unit 5](/ap-macro/unit-5 "fv-autolink") as the case where stabilization policy faces a genuine trade-off.

### [Productivity (Unit 3)](/ap-macro/key-terms/productivity)

A productivity surge acts like a positive supply shock in the short run. But if it's a lasting improvement, it shifts LRAS too, raising full-employment output itself. That's the line between a shock and actual economic growth (EK MOD-2.I.2).

## On the AP Exam

Supply shocks are MCQ regulars and a standard FRQ setup. Multiple-choice stems give you a scenario (an oil price spike, a drought, a productivity boost) and ask what happens to output, employment, and the price level in the short run, or what the economy looks like in the long run after the shock. Practice questions hit exactly these angles, asking things like the short-run price level effect of a positive supply shock and the long-run employment outcome after the shock fades. On FRQs, expect to draw a correctly labeled AD-AS graph showing the SRAS shift, mark the new equilibrium, and then explain the long-run adjustment back to full employment with no policy action. Two things earn points here. Shift the correct curve (SRAS, not AD), and get the directions right. Remember that supply shocks move output and price level in opposite directions, which is the giveaway that distinguishes them from demand shocks.

## aggregate supply shock vs Aggregate demand shock

Both are sudden shifts in the AD-AS model, but they have different fingerprints. A demand shock moves output and the price level in the SAME direction (a positive AD shock raises both, per EK MOD-2.H.1). A supply shock moves them in OPPOSITE directions (a negative SRAS shock lowers output but raises the price level). On the exam, check the scenario. If it changes production costs or productivity, it's a supply shock; if it changes spending by consumers, businesses, government, or foreigners, it's a demand shock. Demand shocks cause demand-pull inflation, supply shocks cause cost-push inflation.

## Key Takeaways

- A negative aggregate supply shock shifts SRAS left, so output and employment fall while the price level rises, which is cost-push inflation and the recipe for stagflation.
- A positive aggregate supply shock shifts SRAS right, so output and employment rise while the price level falls.
- Supply shocks move output and the price level in opposite directions, while demand shocks move them in the same direction. That's the fastest way to tell them apart on an MCQ.
- In the long run, flexible wages and prices undo a temporary supply shock and the economy returns to full employment with unemployment at its natural rate, even without government policy (EK MOD-2.I.1).
- A shock to SRAS never changes potential output. Only a shift in LRAS changes the full-employment level of output, and that represents economic growth (EK MOD-2.I.2).

## FAQs

### What is an aggregate supply shock in AP Macro?

It's a sudden, unexpected shift in the short-run aggregate supply curve, like an oil price spike or a productivity jump. A negative shock lowers output and employment while raising the price level; a positive shock does the reverse.

### Does a negative supply shock cause inflation or recession?

Both at once, which is what makes it nasty. Output falls (a recessionary gap) while the price level rises (cost-push inflation). Economists call this combination stagflation, and it's the signature of a leftward SRAS shift.

### How is a supply shock different from a demand shock?

A demand shock moves output and the price level in the same direction, while a supply shock moves them in opposite directions. Demand shocks come from changes in spending; supply shocks come from changes in production costs or productivity.

### What happens in the long run after an aggregate supply shock?

With no policy action, flexible wages and prices adjust and SRAS shifts back, returning the economy to full employment on the LRAS curve. Unemployment goes back to its natural rate and output returns to potential (EK MOD-2.I.1).

### Does a supply shock shift the long-run aggregate supply curve?

No. A temporary shock only shifts SRAS, and the economy self-corrects back to the same LRAS. LRAS only shifts when full-employment output itself changes, such as through lasting gains in productivity or resources, and that counts as economic growth, not a shock.

## Related Study Guides

- [3.6 Changes in the AD-AS Model in the Short Run](/ap-macro/unit-3/changes-ad-as-model-short-run/study-guide/dZjop0iV2M7iUQ9Rl1FS)

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