After a year filled with uncertainty, 2012 has so far been a strong one for stocks. Stronger economic data has helped push the Dow up more than 8% since January.

But it's not so easy for some investors to forget last year's pain. Many retail players are hanging on the sidelines, waiting for a sign that they won't get burned again.

"There is still some skepticism on the part of people who missed the rally," said Bernard Kavanagh, vice president of portfolio management for St. Louis-based broker Stifel Nicolaus. "So despite the strong initial pop, many retail investors are not in the game yet."