Millionaires are putting their cash to work and moving back into the markets as their confidence in the economy increases, according to a survey by Spectrem Group.

The Spectrem Millionaire Investor Index, which measures the outlook of investors with at least $1 million in investable assets, gained four points to -10 in August. According to the index’s scale, that brings millionaire investors out of a bearish stance and into a neutral stance. Investors haven’t been in the ‘neutral’ category since May when the index reached -2.

Millionaires are also stepping cautiously back into the markets. The number of millionaires “not investing” fell from 9.4% to 6.5% in August. Those planning to invest in stocks rose from 35.2% to 44.4%.

Meanwhile, affluent investors—those with $500,000 or more in investable assets—remained mildly bearish. Spectrem’s Affluent Investor Index rose just one point to -18. That index also reached a high in May of -12.  

The affluent are also more cautious about resuming their investments. The number of affluent investors “not investing” only dropped slightly from 15.1% to 14.6%. The number of affluent investors planning to invest in stocks also remained below their millionaire counterparts, rising from 28.7% to 34.8%.

Bonds were an appealing investment for both groups, with individual bond investing rising from 19.1% to 26.1% and mutual fund bond investing up from 23.9% to 25.7%.

Both millionaire and affluent investors overwhelmingly cited healthcare reform as the main factor affecting their economic outlook. This issue had not even been raised by survey participants in preceding months, but was mentioned by 40% of respondents in August.

“It seems clear that the nation’s wealthiest investors remain cautious, amid uncertainty on multiple fronts, as we move out of summer and into the fall,” said George H. Walper Jr., president of Spectrem Group, in a statement.

The indexes are based on monthly interviews with 250 financial decision-makers who have more than $500,000 in investable assets. The Millionaire Index is based on a subset of this group.