Millionaire confidence plunged by a record amount in May, sparked by fears of government dysfunction in Washington.



The Spectrem Millionaire Investor Confidence Index, a measure of millionaire confidence in the economy and markets, fell 17 points from April. That's the biggest month-to-month drop ever recorded by Spectrem Group, a Chicago-based wealth-research firm that created the index.



The survey found that almost 4 in 10 (39 percent) of millionaires plan to avoid investing in the coming month — the highest percentage since December 2013.



The main reason for the drop: politics and the turmoil surrounding the Trump administration.



The top concern cited by the millionaires surveyed was the political environment.



"Even though the stock market remains at near-record high levels, millionaire investors are becoming increasingly cautious," said Spectrem President George H. Walper Jr. "This is likely due to growing concerns about the weakening political position of President Trump given recent controversies, the declining likelihood of substantive tax reform in the near term, as well as concerns about the recently submitted proposed federal budget."

"Although nonmillionaires also recorded a drop in confidence, the fact they are slightly more confident now than millionaires is a strong indication that we may be entering a tumultuous period for investors," Walper said.



The political pessimism among millionaires is not being driven by Democrats, which would be predictable. The largest drop in the survey came among Republican millionaires.