For high-net-worth investors, the economy may be losing it’s mojo.

The Spectrem Millionaire Investor Confidence Index slid to 6 from 15 the previous month, a 12-month low, while the Spectrem Affluent Investor Confidence Index dipped two points to 6.

Spectrem Group, a Lake Forest, Ill.-based market analysis firm, attributed the declines to an overall drop in economic confidence and concerns over market conditions.

Spectrem president George Walper, Jr., speculated that affluent investors feel that low interest rates are artificially supporting the economy and are expressing uncertainty over a future rate hike.

In May, the Millionaire Investor Confidence Index reached a five-month high, increasing 5 points to 15. Buoyed by positive jobs numbers in May, the Affluent Investor Confidence Index doubled from 4 to 8.

The Spectrem Affluent Investor Confidence Index measures the outlook of American households with more than $500,000 of investable assets, while the Spectrem Millionaire Investor Confidence Index looks at those with $1 million or more.

Confidence is measured on a range from -51, for highly bearish sentiments, to 51, for a bullish outlook. Spectrem considers values between -10 and 10 to be neutral.

This is the first time that the two indexes have been at the same level since February 2010.