Point d’arrêt

A firm should shut down when the market price falls below its average variable cost (AVC) at the profit-maximizing quantity. Continuing production under these conditions would increase losses beyond fixed cost obligations. Shutting down temporarily minimizes losses by avoiding additional uncompensated variable costs, though fixed costs remain due regardless of output level.

The shutdown point is the quantity where market price exactly equals the firm's average variable cost. At this critical threshold, the firm becomes indifferent between continuing production and halting operations. Producing below this point deepens losses, while producing above it allows the firm to cover variable costs and contribute partially to fixed cost obligations.

A firm continues operating when price exceeds average variable cost because revenues cover variable costs and contribute to fixed cost obligations. Since fixed costs persist regardless of production level, continuing minimizes total losses compared to shutting down. This strategy is rational in the short run when the firm expects market conditions to improve.

Average variable cost is the key metric for shutdown decisions. When market price exceeds AVC, the firm should produce because revenues offset variable expenses and reduce overall losses. When price falls below AVC, continuing production only deepens losses beyond fixed cost obligations, making shutdown the optimal choice to minimize economic damage.

Fixed costs remain unchanged when a firm shuts down temporarily. Expenses like building rent must be paid regardless of production level or output quantity. This is why shutdown is preferable to continued production at prices below average variable cost—the firm avoids additional variable cost losses while still bearing unavoidable fixed obligations.

Shutdown is temporary, not permanent. The firm suspends production until market conditions improve and prices rise above average variable cost again. Once the market price recovers sufficiently to cover variable costs and contribute to fixed costs, the firm can resume operations and restore profitability in the short run.

When bread prices drop below the bakery's average variable cost—the cost of flour, labor, and other production inputs—the bakery hits its shutdown point. Continuing to bake and sell at these prices generates losses exceeding fixed costs like building rent. Shutting down temporarily preserves resources until prices recover and allow the bakery to cover variable costs again.