Political opinions of any kind can seriously reduce your investment returns. Anti-free market sentiment and nationalism are among the most harmful biases, though they are by no means the only ones.

In countries where large portions of the population are staunchly opposed to free market capitalism, and harbor strong prejudices against the rich, levels of stock market investment are far lower than in countries where people feel more positive toward free market policies and wealth. This, of course, has a negative affect on investment returns.