Tradesports works a little differently from a stock market, where there is an IPO of a limited number shares. On Tradesports shares are created as traders buy and sell to each other. The more they trade, the more shares are created.

For example, a new market opens. At that time there are no shares to be bought or sold. Trader A comes along and puts up an order to buy 10 shares. He cannot actually buy these shares until someone agrees to (short) sell the shares to him. Trader B sees the order to buy shares and agrees to sell them. Trader A now has a prediction of +10 shares. Trader B now has a (short) prediction of -10 shares. The trade has created the shares. As buyers and sellers keep trading with each other, more shares are created.

In theory an infinite number of shares can be created this way, but there always needs to be traders willing to short sell the shares for this to happen. There is always the same number of shares on the buy side as the sell side, and therefore the losses of one side always equal the profits of the other side.