Where do IRA owners invest their assets? EBRI found that as of 2008 IRA owners put 38.5% of their assets in stocks, 22.3% in money funds, 13.6% in bonds, 12.1% in balanced funds and 13.6% in other assets, the organization announced in a Fast Facts release on Thursday.

IRAs hold more than one-quarter of all retirement assets in the United States, EBRI notes, with a “substantial portion” originally being held in non-IRA plans.

On June 22, EBRI announced that gender plays a very small role in the way IRA owners invest. Both men and women tend to reduce their exposure to equities as they age, EBRI noted. In 2008, men over 70 invested 0.5% more of their assets in equities than women. Men were more likely to invest in assets that fall in the “other” category, while women stuck with balanced funds.

Age, however, does affect how IRA owners invest their money. Investors under age 25 kept almost half of their assets in equities, but older investors reduced their equity allocations to 33%.

Similarly, IRA owners with larger balances also decreased their allocation to equities, although owners with the largest balances ($250,000 or more) diversified their assets across all categories, keeping the highest percentage of assets in bonds, money and other assets.

Roth IRAs had the highest allocation to equities with more than half of assets. EBRI pointed to two reasons for Roths’ higher equity allocations: Roth IRA owners are on average younger than other owners, and Roths tend to be funded by individual contributions only, rather than taking contributions from employers and employees together.

The data is from EBRI’s ongoing IRA Database, which collects data from IRA plan administrators. The database has information on over 14 million accounts and 11 million individuals. Total assets were nearly $733 billion at the end of 2008.