The optimism of U.S millionaires fell to its to lowest level ever in September, according to the latest survey from Spectrem Group.

The firm reported that its Spectrem Millionaire Index declined to an all-time low of five, falling into neutral territory for the first time in 12 months. “Millionaires had been stubbornly optimistic until the September decline, remaining mildly bullish from October 2004 to August 2005 despite the increasing pessimism seen in the overall affluent population,” it notes.

The Spectrem Affluent Investor Index, which measures the investment outlook of households with $500,000 or more in investable assets, remained flat in September at its all-time low of -1. In contrast to the millionaires, the affluent index has been neutral for ten of the past 12 months. The record lows of both indexes date back to their inception in February 2004.

“Affluent investors appeared to be looking past Hurricanes Katrina and Rita in September to longer-term, core issues such as the economy, politics, and oil and gas prices,” the firm says. “In a special hurricane-related question asked of affluent investors, 71% said the Gulf Coast disasters would have little or no impact on their investment decisions over the next six months. These investors cited the economy, the presidential election and results, and oil and gas prices as the most serious threats to their financial goals.”

“It took a while, but millionaires finally have succumbed to the pessimism that has dogged the overall affluent population throughout 2005. All year long, millionaires had represented a source of unusual optimism in contrast to the broader affluent group, which has been neutral since March,” said George Walper Jr., president of Spectrem Group. “However, the September decline in the millionaire index has knocked them out of mildly bullish territory. This represents strong confirmation that the entire affluent population no longer feels very good about the investment environment. And their focus on longer-term issues such as the economy, presidential politics, and oil and gas prices suggests this pessimism may be with us for some time.”

Responding to an open-ended question about the biggest threat to their household financial goals, affluent investors cited: the economy (15%), the presidential election and results (8%), oil and gas prices (8%), unemployment (6%) and health related issues (6%) as their key concerns. Concern about the economy increased from 13% in June, when this question was last asked, and 10% in March.

An even higher percentage of millionaires (20%) cited the economy as their greatest concern. Ranking immediately behind the economy for millionaires were the presidential election and results (14%) and unemployment (9%).

The Spectrem Affluent Investor Index is based on 250, 10-minute telephone interviews each month, giving the data a margin of error of plus or minus 6.2 percentage points. Interviews are conducted with the financial decision-makers in households with $500,000 or more in investable assets. The Spectrem Millionaire Index is based on a subset of the overall survey group that can vary each month. It is typically drawn from more than 100 monthly interviews.