Affluent investors were not spooked by the Ides of March.

The month was a boon for investor confidence, which reached new highs according to the monthly Spectrum Affluent Investor Confidence Survey. The index rose by seven points in March to reach an 11-month high for investors with over $500,000 and under $1 million in investable assets, and millionaire investor confidence also trended up by three points.

“The stock market rally has boosted investor confidence and the level of affluent investors who choose "not to invest" has reached a four-month low,” Spectrem wrote.

The upswing comes after a brief decline in confidence during the month in February, when millionaire investor confidence dropped 10 points due to uncertainty over future household income and the economy. As a result, stock mutual funds showed increased popularity among all investors, according to February’s report.

This month, investors expressed their renewed confidence by moving back into stocks, the report said.

“Equity investment among Affluent investors was at a five-month high in March,” the president of Spectrem Group, George H. Walper, said in a statement. “This rekindled Affluent investor confidence was also reflected in the monthly Spectrem Affluent Household Outlook, which gained nearly 10 points in March, a reflection of more positive attitudes toward the financial factors that impact these investors’ daily lives.”

The outlook was subdued somewhat by uncertainty over gridlock in Washington, particularly surrounding the mandatory spending cuts that went into effect as part of sequestration, Spectrem said. Affluent investors - and millionaire investors, especially - cited the political climate as the most serious threat at the time to their being able to reach their financial goals.

The indices, based on 250 monthly interviews with financial decision-makers who have more than $500,000 of investable assets, are divided into five categories: A reading of 31 to 51 represents a bullish outlook, 11 to 30 mildly bullish, 10 to -10 neutral, -11 to -30 mildly bearish, and -31 to -51 bearish.