Wealthy US families are scurrying from equity markets and holding cash and other ultra-cautious assets in the present volatile market environment, the chief executive of Bessemer Trust said yesterday.

Bessemer Trust, which is a financial advisor to ultra high net worth families, has noted that they are avoiding risk.

"Right now, 50 per cent of our balanced growth portfolio is in cash, bonds and foreign currency," Bessemer chief executive John Hilton said at the Reuters Global Wealth Management Summit. "Historically, we'd hold only 20 to 25 per cent (of cash and bonds) in the portfolio."

That change took place about two weeks ago, he is reported to have said. August was the seventh-most volatile month in the past 1,000 months, he added, a period spanning more than 83 years.

"I think it's very hard to make any sense of it," he said. "There's just a general lack of leadership and a lack of confidence, not just in the US but globally," he added.

"Our clients are tremendously afraid of losing their wealth," Hilton said. "We're more comfortable taking a more defensive position, which will hurt us if markets go straight up, but we don't think they will go straight up any time soon."

Bessemer was formed in 1907 to manage the fortune of Andrew Carnegie's business partner Henry Phipps. The firm opened its doors to other millionaire families in 1975, and since then assets have soared from $1 billion to about $65 billion. It has around 2,000 clients with an average of $30 million in assets.