The Spectrem Affluent Investor Index fell into negative territory in August, dropping six points to an all-time low of –1, primarily due to concern about higher oil prices.

The decline in the index for August, which measures the investment outlook of households with US$500,000 or more in investable assets, represents its third-consecutive decline and the affluent index’s sixth-straight month in neutral territory, Spectrem reports. The index now stands at the lowest level since its debut in February 2004. The prior record low was April’s reading of zero.

Also, the Spectrem Millionaire Index recorded its third-straight decline in August, dropping 1 point to a mildly bullish level of 11. The millionaire index has remained mildly bullish since October 2004.

Higher oil and gas prices ranked by far as the biggest concern of both affluent investors and millionaires last month, Spectrem reports. Nearly half of affluent investors and more than half of millionaires cited higher energy prices as the top news event driving their economic outlook. And, polling for the August indexes took place between Aug. 23 and Aug. 27, even before the sharp energy-price increases caused by Hurricane Katrina.

“Higher oil and gas prices have finally taken their toll on affluent investors, driving their investment optimism to the lowest level since we began tracking it in February 2004. Nearly half of all affluent investors cited rising energy prices as their Number 1 news-driven concern, far outpacing even the Iraq War,” said George Walper, Jr., president of Spectrem. “Millionaires, who tend to take a longer view of investment conditions, if anything were even more worried. With affluent investors remaining neutral for some time now and millionaires stubbornly in the mildly bullish camp, we had assumed some outside influence would be needed to create movement in one direction or another. It looks now like rising oil and gas prices may be that driver.”

The 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 US$500,000 or more in investable assets.