The market is always “just one step away from massive volatility because of programmed trading,” said Michael Yoshikami, the chief executive of Destination Wealth Management, an investment-management firm in Walnut Creek, Calif. “There’s no way that investors can compete with a computer making 1,000 trades a second. What it does is it ramps up the psychology of fear and greed for individual investors.”

Algorithmic trading — proprietary computer programs that can perform thousands of trades a second — has become a reality for global markets. Marko Kolanovic, JPMorgan Chase’s global head of macro quantitative and derivatives strategy, wrote in a report last year that passive and algorithm-driven “quantitative investing” accounted for about 60 percent of stock trades, compared with 10 percent from more traditional trades.