The eurozone crisis subsided for much of December, but it may return with a bang early in 2012. Here are five key risks investors should have on their radar in the first quarter.

First, Greece aims to conclude its "voluntary" bond swap in January, chopping €100bn off its debt and over time reducing the debt-to-GDP ratio to 120% from more than 160%. However, it's not clear that enough investors will sign up, potentially throwing the swap and Greece's bailout into disarray. Even if they do, the fear remains the deal doesn't do enough. The International Monetary Fund may yet conclude Greece's debt is unsustainable and stop lending.