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Market Equilibrium and Adjustments

Sep 20, 2025

Overview

This lecture explains the concept of market equilibrium, using demand and supply curves to show how prices adjust when markets experience excess supply or excess demand.

Market Equilibrium

  • The equilibrium point (E) is where the supply and demand curves intersect.
  • At equilibrium, the quantity supplied equals the quantity demanded.
  • Neither producers nor consumers have an incentive to change their behavior at equilibrium.
  • Equilibrium is reached in the absence of external shocks or interference.

Excess Supply (Surplus)

  • Occurs when the price is set higher than equilibrium.
  • At this higher price, quantity supplied exceeds quantity demanded.
  • Excess supply means producers have unsold goods.
  • Producers lower prices to sell off excess goods, pushing the price toward equilibrium.

Excess Demand (Shortage)

  • Occurs when the price is set lower than equilibrium.
  • At this lower price, quantity demanded exceeds quantity supplied.
  • Excess demand means consumers want more than is available.
  • Producers raise prices, which reduces demand and increases supply, moving price toward equilibrium.

Market Adjustment Process

  • Prices above equilibrium lead to downward pressure (due to surplus).
  • Prices below equilibrium lead to upward pressure (due to shortage).
  • These market forces ensure that the price moves toward equilibrium over time.

Key Terms & Definitions

  • Equilibrium — The price and quantity where supply equals demand, and the market is stable.
  • Excess Supply (Surplus) — When quantity supplied is greater than quantity demanded at a given price.
  • Excess Demand (Shortage) — When quantity demanded is greater than quantity supplied at a given price.
  • Market Forces — The actions by buyers and sellers that drive price adjustments toward equilibrium.

Action Items / Next Steps

  • Review demand and supply curve basics if needed (as referenced in the lecture).
  • Understand how market forces correct prices when not at equilibrium.