The way Sweden taxes stocks is to give people a choice between two options. They can either tax the total change in ownership value between each year (profit vs loss), or to pay a fixed (lower) tax on the total value regardless of profit or loss.

The first option guaranties that you don't pay more in taxes than you earn on the stocks, and the later has higher risk vs reward. For some reasons, the later seems to be the most popular choice, despite the risk that the owner need to cover the cost of taxes regardless of what happens in the stock market.