Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-1454_5h26.pdf
Page Number: 9

Cite as:  585 U. S. ____ (2018) 

5 

Opinion of the Court 

merchants  who  accept  it.  Muris  522;  Evans  &  Schma-
lensee 692.  Networks can then charge those merchants a 
fee  for  every  transaction  (typically  a  percentage  of  the 
purchase price).  Striking the optimal balance of the prices 
charged  on  each  side  of  the  platform  is  essential  for  two-
sided  platforms  to  maximize  the  value  of  their  services 
and to compete with their rivals. 

B 
Amex,  Visa,  MasterCard,  and  Discover  are  the  four 
dominant  participants  in  the  credit-card  market.    Visa, 
which  is  by  far  the  largest,  has  45%  of  the  market  as
measured by transaction volume.3  Amex and MasterCard 
trail  with  26.4%  and  23.3%,  respectively,  while  Discover
has just 5.3% of the market.

Visa  and  MasterCard  have  significant  structural  ad-
vantages over Amex.  Visa and MasterCard began as bank 
cooperatives and thus almost every bank that offers credit 
cards is in the Visa or MasterCard network.  This makes it 
very  likely  that  the  average  consumer  carries,  and  the 
average  merchant  accepts,  Visa  or  MasterCard.    As  a 
result, the vast majority of Amex cardholders have a Visa 
or MasterCard, but only a small number of Visa and Master-
Card  cardholders  have  an  Amex.    Indeed,  Visa  and 
MasterCard  account  for  more  than  432  million  cards  in 
circulation  in  the  United  States,  while  Amex  has  only  53
million.    And  while  3.4  million  merchants  at  6.4  million 
locations accept Amex, nearly three million more locations
accept Visa, MasterCard, and Discover.4 

—————— 

3 All figures are accurate as of 2013. 
4 Discover  entered  the  credit-card  market  several  years  after  Amex,
Visa,  and  MasterCard.    It  nonetheless  managed  to  gain  a  foothold
because  Sears  marketed  Discover  to  its  already  significant  base  of
private-label  cardholders.    Discover’s  business  model  shares  certain 
features  with  Amex,  Visa,  and  MasterCard.    Like  Amex,  Discover 
interacts directly with its cardholders.  But like Visa and MasterCard,