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An aggregate demand shock happens when total spending in the economy changes suddenly because of shifts in consumer confidence, business investment, or government policy.

Demand shocks are of two types: negative and positive.

A negative demand shock happens when consumers cut back on purchases or firms delay investment, reducing total spending across the economy.

On the graph, this decline shifts the aggregate demand curve leftward, from AD₁ to AD₂, creating a recessionary gap. The economy moves to a new short-run equilibrium point F.

At point F, output falls from Y₁ to Y₂, and the price level decreases from P₁ to P₂. Wages and prices adjust slowly. As a result, businesses face declining sales, which lead them to reduce production and lay off workers in the short run.

A positive demand shock, such as a rise in consumer spending, government expenditure, or exports, would shift the aggregate demand curve rightward, from AD₁ to AD₃. Output and prices both increase, creating inflationary pressure.

In conclusion, aggregate demand shocks cause short-run fluctuations in output and prices.