Third-quarter 2012 data for defined-contribution plans administered by Springfield, Mass.-based MassMutual Financial Group show that, combined, generation X and generation Y participants now account for 55 percent of the company's participant count, compared with 41 percent of baby boomer participants.

Baby boomers still control the lion's share of assets at 61 percent, with the combined gen X/gen Y group holding 31percent of all defined-contribution plan assets at MassMutual.

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 the company says is well above the industry average. Gen Y participants (born between 1982 and 1995) led with 49.8 percent for the quarter versus 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, or stocks, at 45 percent for the quarter endedSept. 30, compared with gen Y savers at 32 percent and baby boomers at 38 percent.

Women continue to favor age-based investments, which take into account a person's age and reallocate assets into more conservative holdings as retirement nears, far more than risk-based options. Women opt for age-based investments more than 2.5 times as much—at 72 percent versus 28 percent, respectively. Men remain more evenly divided on their preferences, with approximately 52 percent in age-based versus 48 percent in risk-based investments.

Average account balances for women grew 3.9 percent for the quarter versus 4.2 percent for men, reflective of the generally more conservative investing profile of women.

In terms of account balances, the gender gap continues to close, albeit at a slow rate. Average account balances for women now trail those of men by 38.4 percent, a slight improvement over a high of 40.5 percent in late 2010.

"Not surprisingly, gen Y savers are taking full advantage of asset-allocation investment options," saysElaine Sarsynski, executive vice president of MassMutual's retirement services division and chairwoman and CEO of MassMutual International LLC. "We are so pleased to see that younger generations appear to understand the importance of starting early to save for retirement."

MassMutual says its percentage of participants who initiated loans in the third quarter (1.7 percent) was at its lowest level in four years and is significantly lower than the industry average.

"We strive to educate participants that taking a loan from the 401(k) can have negative consequences and should be a last resort. We are very pleased that their behavior indicates they are grasping this message," Sarsynski says.

MassMutual serves approximately 1.6 million plan participants. Founded in 1851, the company offers life insurance,disability income insurance,long-term care insurance,retirement/401(k) plan services, andannuities.

MassMutual Financial Group is a marketing name for Massachusetts Mutual Life Insurance Co. (MassMutual) and its affiliated companies and sales representatives. MassMutual's major affiliates include: Babson Capital Management LLC; Baring Asset Management Ltd.; Cornerstone Real Estate Advisers LLC; The First Mercantile Trust Co.; MassMutual International LLC; and MML Investors Services LLC, among others.