Millionaires appear to have more investment confidence than they have had in three years, according to one index.

Spectrem Group, based in Chicago, announced today that its Spectrem Millionaire Investor Confidence Index rose 7 points in December to end the year at 7. This increase brings the millionaire index to its highest level since December 2007, when it stood at 8, and keeps it in neutral territory.

However, the simply affluent don't appear as optimistic. The Spectrem Affluent Investor Confidence Index, which measures the investment confidence and outlook of households with $500,000 or more in investable assets, remained unchanged at -8, also a neutral reading.

"Millionaires posted a strong increase in investment confidence in December, bringing 2010 to a close at their highest level in three years. Meanwhile, the broader affluent population's confidence remained unchanged. With November's midterm elections bringing a shift in the political climate, America's wealthiest investors appear hopeful that their lingering economic concerns will ease as we move forward into the New Year," said George H. Walper, Jr., Spectrem Group's president.