Offering versus Choice in 401(k) Plans: Equity Exposure and Number of Funds
基于60多万个401(k)计划参与者的数据，发现参与者倾向于将缴款平均分配到所用基金中，且所用基金数量（通常3-4只）对计划提供的基金数量不敏感，股票基金配置比例对股票基金占比也不敏感。
ABSTRACT Records of over half a million participants in more than 600 401(k) plans indicate that participants tend to allocate their contributions evenly across the funds they use, with the tendency weakening with the number of funds used. The number of funds used, typically between three and four, is not sensitive to the number of funds offered by the plans, which ranges from 4 to 59. A participant's propensity to allocate contributions to equity funds is not very sensitive to the fraction of equity funds among offered funds. The paper also comments on limitations on inferences from experiments and aggregate‐level data analysis.