Firms and Competitive Markets. Competitive Market Properties – Many buyers and sellers – Trading...
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Transcript of Firms and Competitive Markets. Competitive Market Properties – Many buyers and sellers – Trading...
Firms and Competitive Markets
Competitive Market• Properties– Many buyers and sellers– Trading identical products– Each buyer and seller a price taker– Free entry/exit of the market
• Goal is to maximize profit– ∏ = TR - TC
• Total Revenue– Price time quantity: TR = P x Q
• Average Revenue– Total Revenue divided by quantity sold
• Marginal Revenue– Change in revenue from additional unit sold
• For competitive firms– Average Revenue = P– Marginal Revenue = P
Profit Max• Profit Maximization– Produce at the quantity that maximizes the
difference between TR and TC– Compare marginal revenue with marginal cost• If MR > MC increase production• If MR < MC decrease production• If MR = MC profit maximized
Costs and Revenue
Quantity
MC
ATC
AVCP = MR
= AR
Q*
Profit Max Decision
Producing here MC > MR so don’t
Producing here MC < MR so produce more
MC = MR so profit maxed
• Marginal Cost Curve (MC) determines the quantity a firm would be willing to supply at a given price
• Therefore it is the firms supply curve
Costs and Revenue
Quantity
MC
ATC
AVC
P1
Q1 Q2
P2
MC Curve as Supply Curve
Shut down and Exit• Shut Down– Short Run decision not to produce– Still have to pay fixed costs though
• Exit (don’t Enter)– Long Run decision– No costs
Short Run Decision• Focus on– Total Revenue– Variable costs (fixed costs are fixed, so ignore)
• Decision– Shut down if TR < VC ( or MR/AR < AVC )
• Competitive Firms Short Run Supply Curve– MC curve above the AVC curve
MCATC
AVC
Costs
Quantity
In short run firms produce on the MC curve if P > AVC
In short run firms shut down if P < AVC
Short Run Supply Curve
Long Run Decision• Exit Market if:– TR < TC– Or P < ATC
• Enter Market if:– TR > TC– Or P > ATC
• Competitive Firms Long Run Supply Curve– Portion of the MC curve above the ATC curve
MCATCCosts
Quantity
In long run firms produce on MC curve if P > ATC
Firms exit market if P<ATC
Long Run Supply Curve
Profit• If P > ATC– Positive profits– ∏ = TR – TC = (P – ATC) x Q
• If P < ATC– Negative profits (losses)– Loss = TC – TR = (ATC – P) x Q
P
AVC
Q*
Profit
Profit Maximizing QQ*
Loss
Cost Minimizing Q
MCMC
AVC AVC
P
AVC
Firm with Profits Firm with Losses
Market Supply Curve• In short run # of firms fixed• Each firm supplies where P = MC• Each firms supply curve is the MC curve above
their AVC curve (otherwise 0)• For market supply just add up horizontally
+ =
S1 S2 S - Market
• In long run # of firms not fixed– Free entry/exit
• If P > ATC– Profits are positive– Firms enter market
• If P < ATC– Firms taking losses– Firms exit the market
• This means all firms (assuming identical cost curves) will produce at MC = ATC (efficient pt)– So MKT supply curve will be horizontal at that
point (perfectly elastic)
P = Min ATC
MCATC
Supply
PricePrice
Quantity Quantity
Multiple Firms with identical cost curves
Add up supply at MC = ATC level for each to get Market Supply
Long Run Market Supply
Some Caveats
P
Q
Actual Supply would be more like this, with holes and dots denoting when different firms enter. That is it would not be a smooth line.
And perhaps it could still slope up if by increasing market size they bid up the cost of inputs. This would cause latte entering firms to have higher cost curves.
P
Q
Or some firms could just be better at it, thus having lower cost curves. But either way LR flatter than SR.
• So why stay in business if making zero profit?• Profit = Total Revenue – Total Costs• Total Costs include opportunity costs• Zero Profit Equilibrium– Zero economic profit– Positive accounting profit
Shift in Demand and LR and SR supply response
• Market in long run eq. – P = ATC– Zero economic profit
• Increase in demand– Demand shifts out– Short Run• Higher quantity, higher price• P > ATC• Positive economic profit
• Because of positive profits• Firms enter in the long run• SR supply curve shifts right• Price falls back to low point on ATC• Quantity increases (because of more firms)• Back to efficient scale
Market Firm
D SR Supply
LR Supply
MCATC
P P
Q Q
Initial State of Equilibrium
P’
Q’
Market Firm
D SR Supply
LR Supply
MCATC
P P
Q Q
Demand Shifts, + Profits
P’’
Price increases
Which leads to + profits
Market Firm
DSR Supply MCATC
P P
Q Q
Supply Shifts, 0 Profits
P’’’
Profits induce firms to enter market
Restoring Long Run Equilibrium, but with more firms
Price falls back