Two of the four front-runners in the Italian election are convicted criminals. Such is the state of politics in this highly-indebted country as Italians go to the polls this weekend to choose a new government.

Recent market action shows global investors are nervous about the outcome. Italy's stock market sold off sharply on Thursday and its interest rates have started to rise again. The reason: It is quite possible that no party wins a strong mandate—leading to an unstable government, paralyzed by infighting, and unable to fix Italy's finances.