Most people think the stock market is a zero sum game because there is a buyer for each seller and seller for each buyer so each cancels the other and everything is equal. Not quite.There are losers here, both the buyer and the seller because each one paid a commission to buy and a second commission to sell. This eats away at the profit of the winner and adds to the loss of the seller if he sold for less than he paid.How does buying and selling of a stock effect the company? When you buy GM stoc.