Gen X and Gen Y retirement plan participants now account for 55 percent of MassMutual's defined contribution plans in the third quarter of 2012, compared to 41 percent of baby boomer participants. Third quarter data from MassMutual shows that baby boomers still control 61 percent of assets, with Gen X and Gen Y holding a combined 31 percent of all defined contribution plan assets on MassMutual's platform.

The percentage of MassMutual's total participant assets in age-based and risk-based options reached an all-time high during the third quarter of 2012, accounting for 26.6 percent of total defined contribution plan assets under management, which is well above the industry average.

Gen Y participants (born between 1982 and 1995) led with 49.8 percent for the quarter vs. Gen X (born between 1965 and 1981) at 29.8 percent and baby boomers at 22.6 percent. Significantly, Gen X participants had the highest allocations in equities at 45.6 percent for the quarter ended September 30, compared with Gen Y savers at 32.2 percent and Baby Boomers at 38.4 percent.