Investment confidence sank among affluent individuals and millionaires in December, according to a monthly survey issued Wednesday.

The Spectrem Affluent Investor Confidence Index fell five points to -15, returning to mildly bearish territory.

The decline in the index, which measures the investment confidence and outlook of households with $500,000 or more in investable assets, follows a five-point gain in November. It ends the year with the affluent index mildly bearish for 11 of 12 months.

The Spectrem Millionaire Investor Confidence Index fell six points in December to -10, its fifth-straight month in neutral territory.

“While more positive on the economy, rising concerns about the political climate are making wealthy Americans a little less optimistic heading into the New Year,” said George H. Walper, Jr., the president of Chicago’s Spectrem Group, which produces the monthly survey.

In response to an open-ended question about the most serious threat to achieving their financial goals, affluent investors in December cited: the political climate (22%); the economy (18%); unemployment (12%); market conditions (6%); inflation (6%); and health-related issues (4%). Those choosing political climate rose from 16% in September, the last time this question was asked. Those citing the economy fell from 24%.

Millionaires expressed more concern about the political climate (24%) than the affluent but less about the economy (16%).

The Spectrem Affluent Investor Confidence Index is based on 250 monthly interviews. The millionaire index is based on a subset of the overall survey group.