Investors raised their cash reserves to the highest level in a year in December as they prepared for a jittery 2012 with growing concerns over the eurozone debt crisis, although some dipped back into cheap equities, according to Reuters polls of investment houses and fund managers.

The surveys of 56 leading investment houses in the United States, continental Europe, Britain and Japan showed that a typical balanced portfolio held 6.6 percent of its assets in cash, the highest proportion since at least December 2010, from 6.4 percent last month, Reuters said.

The polls also showed exposure to stocks rose to 51.3 percent, the highest since July, from 50.6 percent, led by U.S. and Japanese investors.

Bonds fell to 34.3 percent from 35.3 percent, the lowest since March.

Within equities, Britain and emerging Asia gained in popularity, while allocation to North American and eurozone stocks fell.

In their fixed-income portfolios, investors cut allocation to government debt to 51.3 percent — the lowest in at least a year — and increased exposure to high-yield bonds to 14.7 percent.

U.S. money managers rebuilt their equity holdings in December to the highest point this year on signs of a strengthening U.S. economy. The poll of 12 fund managers showed firms boosting their equity allocations for the second month in a row to an average of 66.8 percent, Reuters said.