The Chicago-based consulting firm, Spectrem Group, announced that its index of millionaires’ investor sentiment slipped from mildly bullish to neutral in September.

The Spectrem Millionaire Index fell to a neutral level after seven consecutive months in mildly bullish territory, bringing the millionaires it surveys in line with the broader affluent population. Affluent investors have held a neutral investment outlook since July.

The index, which measures the investment outlook of households with investable assets of US$1 million or more, recorded its third straight decline in September and dropped to the lowest level since its inception in February 2004. Its sister index, the broader Spectrem Affluent Investor Index, which looks at households with US$500,000 or more in investable assets, also recorded its third straight decline last month, edging closer to bearish territory.

“Millionaires have been measurably more optimistic than affluent investors through the bulk of this year, only now losing their last hint of bullishness,” said George Walper Jr., president of Spectrem Group, in a release. “When asked about the most serious threats to their financial goals, these millionaires expressed far more concern about terrorism than affluent investors as a whole — with terrorism ranking behind only economic performance. If news from the Middle East is starting to take such a toll on this generally more patient and positive group, it is not at all clear that sentiment will rebound once the U.S. November election is behind us.”

Affluent investors showed somewhat more concern about the economy, the presidential election, terrorism and household income than when asked about threats to their financial goals in July. The affluent group was less concerned about stock market performance than it was in July.

The indexes are derived from phone interviews with investors, and the data has a margin of error of plus or minus 6.2 percentage points.