The 3 countries that owe the most money to the IMF are Greece, Ireland and Iraq.

I’m not an expert, but I can think of a few reasons why these 3 countries owe so much money to the IMF.

Greece and Ireland have relatively large economies, which means they have large budgets. Naturally, large budgets come with larger than usual debt obligations. When rich countries default on their debt, they would require a larger bailout than countries with small GDP.

Also, Ireland and Greece are in the Eurozone. This means they have strategic importance. Had either one of these countries defaulted in their debt obligations, the entire EU, and by extension the entire world economy, would’ve been hit. The IMF, tasked with maintaining global financial stability, believes that diverting scarce resources to such countries is in all of ours’ best interest.

The United States is the largest contributor to the IMF. This fact causes some friction. The reason is that the IMF is designed in such a way so as to give each country a share of the total vote on the basis of relative money contributions. But the US is the only country that gets a smaller share of the vote than the share of how much money it contributes.