all Flashcards
perfect comp characteristics
atomistic - large number of buyers and seller
homogenous product
perfect knowledge
no collaboration
free to leave and enter a market
oligopoly characteristics
- Large buyers => small producers
- May have perfect information
- Identical or different products
- firms interact and make decisions based on others in order to max profits
- some barriers
oligopoly topology
Cournot Model:
OUTPUT
- Each firm picks a level of output based on assumption other firm output is fixed
e.g. airlines decide number of flights then charge based on WTP
Bertrand Model:
PRICES
- Firms pick price level that maxes profits assuming other firms prices are fixed
Cournot Model Assumptions
- Homogenous product
- Duopoly, only two firms operate
- Identical cost structure
- Each firm sets its own output (Q) to max profit given other output
- Each firm treats others output as fixed when making its own output decision
Zero Conjectural Variation Assumption (ZCVA)
Expected change output in Firm when firm A changes output
QeB/QA = 0, QeA/QB= 0
Isoprofits
- Show all combos of Qa and QB which produce identical profits for a firm
- Concave to axis
- Closer to axis represents higher profits
Reaction functions
Shows level of output that would max profits for firm
- Further to the right of RFa, firm B produces less
-> therefore firm a can obtain more market share
Cournot-Nash Equilibrium
- Assume both firms have identical costs
- Equilibrium because both firms max profits given the output of the other
- Stable, no incentive to move
- Non-Cooperative equilibrium
- Market automatically reaches stable
- Dont try to influence
C-N Monopoly
If one firm does not produce anything => the other is a monopoly
M - evenly shared monopoly output
Output at M < C-N
Profit at M > C-N
Output at PC > C-N
Profit at PC < C-N
Weaknesses of Cournot-Nash
Each firm takes output as given (ZCVA) which is unrealistic:
-> Under ZCVA, firms dont realise their actions have effect on competitor
=> limits firm to only aim for C-N
-> In reality could tacitly collude/cooperate and aim for M where both make higher π
Still allows to identify outcome of no cooperation or after cooperation breaks down
Forms of collusion
Cartels:
- In which members fix quantities or prices subject to explicit rules and monitor compliance with penalties with cheats
Examples of Cartels
Bridgestone Tyres
- Manipulated the prices of antivibration rubber parts (£255M) US DOJ
Libor price thinking
China fined 12 japanese car part manufacturers for price fixing 1.2 bn yuan
- Under China’s anti-trust law, which was enacted in 2008, authorities can fine a company as much as 10% of its annual revenues.
Libor Scandal
In 2012, some banks falsely reported their rates that they periodically report in the interbank market.
rig key rate of London interbank lending rate
- There was liquidity concers from 2007 crisis. Barclays manipulated libor sumbissions to give a healthier picture of banks credit quality and ability to raise funds
Tacit Collusion
Firm influence market outcomes without formal agreements or commitments between firms
Conjecture approach
Based on conjecture that firms make about reaction of other firms
Dropping ZCVA
- Cooperation appears (use output to influence one another)
- Tacit collusion = no agreement
- C-N is no longer a stable equilibrium, more incentivised to move to M (Chamberlain joint profit max)
Size of conjecture => degree of the effectiveness of collusion
Game Theory
Study how independent agents make decisions under uncertainty
Different types:
- Single period vs multi period
- Simultaneous vs sequential
- Constant sum or nonconstant sum
- Zero sum game
Prisoner dilemma
What is the dominant strategy of each firm
-> best strategy no matter what competitor does
-> whichever returns highest profit
C-N = High/High
M = Low/Low
M in prisoner dilemma
By dropping assumptions can reach M
- Allow communication - cooperation is likely
- Allow for repeated games, firm can realise influence, coop likely
=> repeated games with small reaction lags dissuades cheating
Tit For Tat assumptions
- Two players
- Sequential moves to produce lower/higher output
period t:
A Produce low
Period t+1:
B produce low = πCoop
B produce high = πCheat
period t+2:
A retaliate to high = πcheat
leads to πcheat from then on
or leads to πcoop onliy
- no communication
- infitinte repetitions of the game
Coop Condition
PV Coop > PV Cheating
πCoop +πCoop/r > πCheat + πC-N/r
PV Coop(Low)
πCoop + πCoop/r
PV Cheat(High)
πCheat + πC-N/r
Isolating R
r - discount rate
- Lower the interest rate more likely coop is
r < (πCoop-πC-N)/(πCheat-πCoop)
πCoop-πC-N - reward for cooperation, the greater this is the more likely to coop
πCheat-πCoop - reward for cheating. the smaller the more likely coop is