Despite recent stock market gains, wealthy investors remain ambivalent about the economy.

Affluent investor confidence maintained a 12-month high this month, while millionaire investment confidence fell slightly, according to Spectrem Group monthly research, which was released Wednesday.

The Spectrem Affluent Investor Confidence Index, which measures the economic and investment confidence of households with investables exceeding $500,000, remained at 2, the same reading as a month earlier, but the Spectrem Millionaire Investment Confidence Index, which gauges the confidence of those with investables over $1 million, dropped to 5, down from 8 the previous month.

“Affluent investors are saying, ‘Gee, I’m a little concerned because of the record highs, so maybe I’ll be keeping a little more money on the sidelines,’” said George H. Walper, Jr., president of Spectrem. “They don’t want to buy when the market’s at a high.”

Stock market conditions and unemployment were the major factors influencing the economic outlook of affluent investors, according to Spectrem. Sequestration and political gridlock in the nation’s capital played less of a role than in prior months.

Affluent investors were also more inclined toward investing than millionaires.

“Affluent investors in May expressed an increased interest in safer, more conservative vehicles such as bonds [and] cash,” Walper said in a statement. “Given recent market levels, it is not surprising. It indicates their continued wariness that this year’s record high market rallies will continue.”

Despite the somewhat mixed signals, wealthy investors were more positive about the financial circumstances affecting their daily lives. Spectrem’s Affluent Household Outlook survey surged to its highest level in nearly 30 months in May, indicating the potential for increased investment in the months ahead.