Market losses last year have prompted U.S. foundations to cut back on their planned donations in 2009, according to a new survey.

Of the 350 foundations surveyed, about half suffered portfolio losses of 20% or more in 2008 and 30% endured losses of between 10% and 20%. Just 12% of the foundations broke even or achieved gains in their portfolios.

The joint survey by Citi Institutional Consulting and the Association of Small Foundations (ASF) also found that more than 60% of the foundations plan to reduce their grant budgets by between 10% and 50%. Some foundations said they will no longer accept new grant applications or designate new grantees, and will avoid multi-year commitments.

Most foundations said they foresaw few changes in their asset allocations and would continue with their long-term investing strategies, according to the survey.

“In the face of very challenging circumstances, our members are trying to minimize the damage to their foundations and maximize the ability to fulfill their missions," said Tim Walter, CEO of ASF. "What this tells us is that small foundations are doing their utmost to balance responsiveness and prudence."