Michael Santoli at Barron's has done some thinking about what could slow or reverse the 2010 rally in stocks.

Yet a disproportionate amount of that earnings increase is anticipated to come from energy and financial stocks. These are two notoriously tough sectors to handicap, and also two of the lowest-multiple groups, implying the market wouldn't advance dollar for dollar even with such profit gains. The median stock's current 12-month-forward earnings-growth forecast is above 15% now, suggesting that expectations are getting pretty aggressive.