Input price discrimination with passive partial ownership

Passive partial ownership (PPO) is commonly practised in many industries. When operating profits of stock-owned firms decrease, stock-holding firms will increase output to reduce capital gain through owned firms' stocks. In a vertically related market with downstream PPO, consumer and total surpluses when input price discrimination is allowed may be larger than when it is banned because PPO mitigates effects of reduction in output caused by higher input price.