Nearly two-thirds of nonprofit groups are diversifying their investments as a hedge against stock-market volatility, with many looking to private equity and commodities, according to a new survey by financial advisory firm SEI.

In a news release, the company said 64 percent of 110 nonprofit executive and investment-committee members it polled have spread their portfolios into new asset classes the year. Almost of the quarter of the respondents have at least 31 percent of their organization’s money in such illiquid investments.

The respondents represent endowments and foundations with more than $1-billion in collective assets, none of which are currently handled by SEI. More than half said they are using outside investment managers and 24 percent are considering doing so by the end of 2012.