Definition

Léon Walras, in Éléments d’économie politique pure (1874), explained equilibrium as the point where the plans of buyers and sellers are mutually compatible: the price at which quantity demanded equals quantity supplied. (Walras, Léon. Éléments d’économie politique pure)

Introduction

Imagine a weekly vegetable market. At ₹40 per kilogram, there are too many buyers for tomatoes compared to what sellers bring — a shortage! At ₹100 per kilo, sellers bring in heaps, but buyers vanish — a surplus! Somewhere in between, there’s a price (say ₹70) where the amount buyers want matches what sellers supply. That “sweet spot” is market equilibrium.

Explanation

• Equilibrium Price (P*)
  The price at which demand equals supply.

• Equilibrium Quantity (Q*)
  The traded quantity at P*.

• Disequilibrium
  • At price above P* → surplus (excess supply).
  • At price below P* → shortage (excess demand).

• Adjustment Mechanism
  Competition pushes prices toward equilibrium:
  • Surplus → sellers cut price → demand rises, supply falls → back to P*.
  • Shortage → buyers bid up price → supply rises, demand falls → back to P*.

This concept underpins how decentralized markets “self-correct” under competitive conditions.

Diagram

• The Demand curve (D) slopes downward.

• The Supply curve (S) slopes upward.

• They intersect at the equilibrium point (P*, Q*), where market demand equals market supply.

Real-World Case

Smartphone Pricing in India
When a new budget model is launched at a too-high price, units pile up in warehouses (surplus). Retailers slash prices until demand catches up — reaching equilibrium. Conversely, when a hot model is underpriced, stocks vanish instantly (shortage) and prices rise in resale markets.
Reference: Counterpoint Research. India Smartphone Market Report 2023

Key Takeaways

• Market equilibrium occurs where quantity demanded = quantity supplied.

• Prices above equilibrium create surplus; prices below equilibrium create shortage.

• In competitive markets, forces of supply and demand push prices toward equilibrium.

• Real markets often fluctuate around equilibrium but the principle is the anchor.