Portfolio managers at Bessemer Trust, financial adviser to ultra-wealthy U.S. families, took an extremely defensive posture a few weeks ago amid some of the most volatile financial markets in more than 80 years. A sluggish U.S. recovery, an expanding debt crisis in Europe and political deadlock are just some of the factors contributing to wild ups and downs in stock prices. As markets convulse with growing frequency, often for no apparent reason, many small investors are heading to the sidelines. Now, apparently, families with tens of millions of dollars at their disposal are also fleeing the market. "Right now, 50 percent 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 on Wednesday. "Historically, we'd hold only 20 to 25 percent (of cash and bonds) in the portfolio." That change took place about two weeks ago, he said. August was the seventh