401(k) plan participants tend to use no more than three or four...

401(k) plan participants tend to use no more than three or four investment options each, according to the records of more than 600 401(k) plans studied by two Columbia University researchers. The study, "Offering vs. Choice in 401(k) Plans: Equity Exposure and Number of Funds," by Wei Jiang and Gur Huberman, also says that participants tend to allocate their contributions evenly across the investment options they use. Plan sponsors "should offer a mix of funds that could give participants good diversification with a limited number of funds," Ms. Jiang said in an interview.