Ebrahim AlhamedFrameworks Library

m.03 · I · The Market Mechanism · Shocks & Elasticity

When Something Moves

Every intervention has a deadweight loss — know who bears it.

Markets move when supply or demand shifts. The magnitude of the price and quantity response depends on elasticity — how sensitive each side is. Inelastic markets pass shocks into price; elastic markets pass them into quantity. Government interventions (tax, subsidy, tariff) create deadweight loss, and the incidence of that loss splits based on the same elasticity. — after Myatt & Galeotti

The shock transmission.

A supply or demand shift moves the equilibrium. How much of the move is price vs quantity depends on the slopes.

Supply and demand Supply and demand curves crossing at equilibrium, with a shifted curve showing a new equilibrium — price on the vertical axis and quantity on the horizontal axis. D S equilibrium new equilibrium quantity price

The levers in the machine.

Shock Propagation · Galeotti
Supply shocks (cost, tech, regulation) · Demand shocks (income, preferences)
Supply curve shifts right → price ↓, quantity ↑. Demand curve shifts right → both rise.
Price Elasticity · Mankiw-Taylor
E = %ΔQ / %ΔP · elastic |E| > 1 · inelastic |E| < 1
Incidence of a shock falls on the less-elastic side. (Markup rule (P−MC)/P = 1/|E| is the monopoly application — see m.04.)
Government Interventions · Myatt
taxes · subsidies · price controls · tariffs
Any price away from equilibrium creates deadweight loss. Incidence splits by elasticity.
Substitutes & Complements · Galeotti
cross-price elasticity
Shocks ripple into related markets. Substitutes gain; complements lose.

When a shock hits your industry.

  1. Supply or demand shock? Which curve moved?
  2. How elastic is each side? Inelastic demand + inelastic supply = big price move, small quantity move.
  3. Who bears the incidence? The more inelastic side absorbs more of the burden.

Key reading · Supply and Demand Shocks · Galeotti

Elasticity determines transmission.

Elastic markets adjust quantities; inelastic markets adjust prices. A manager's job during a shock is to know which side of the market is more elastic — because that is who is about to carry the cost.

Who moves first in the face of a shock? Whoever can.

← m.02 Supply, Demand & the Cost Taxonomy ··· m.04 The 1/2 Rule & Cournot →