Spectrem Group's Affluent Investor Index fell 6 points in August to a reading of negative one on surging concern about higher oil and gas prices.

The August decline in the index, which measures the investment outlook of households with $500,000 or more in investable assets, represents its third-consecutive decline and the affluent index's sixth-straight month in neutral territory.

At negative one, the index now stands at the lowest level since its debut in February 2004. The prior record low was April's reading of zero. The Spectrem Millionaire Index also recorded its third-straight decline in August, dropping one 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. Nearly half of affluent investors and more than half of millionaires cited higher energy prices as the top news event driving their economic outlook.

Polling for the August indexes took place before the sharp energy-price increases caused by Hurricane Katrina.

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