The S&P 500 index passes 1,500. The Dow Jones closes above 14,000 for the first time since the financial crisis. Individual investors start returning money to the stock market.

As encouraging as these stories are, headlines alone don’t make the case that U.S. equity markets will continue plowing ahead. But we think there’s plenty of evidence that 2013 could be the fifth consecutive year that equity investors climb the “wall of worry.”

There are still big-picture risks to get hung up on — that’s been true for years. Lately the potential drag of U.S. fiscal austerity seems to have displaced Europe’s sovereign crisis and the China slowdown as investors’ biggest worry. But despite the preoccupations, stocks finished on positive ground in 2009, even coming off a brutal, multiyear tailspin. They were up again in 2010. And in 2011. And in 2012. Four straight years of positive returns. Volatile, yes, but also up. ....