BOSTON (AP) — Europe’s on-again, off-again progress in tackling its debt problems has kept U.S. investors on edge for the better part of two-and-a-half years. It seems like this ride should be over by now, but it isn’t. Risks continue to grow.

An election in Greece on Sunday could be a turning point in the crisis. A newly popular leftist political party wants to renegotiate or scrap austerity measures agreed to as part of Greece’s bailout. If it wins, that could lead to Greece’s exit from the group of 17 countries that use the euro.