Goldman’s Rubner Sees Deeper Stock Losses in a ‘No Rules Market’

The two-month selloff in US stocks threatens to intensify as options dealers on Wall Street and fast-money traders both turn against the market.

Such is the warning from Goldman Sachs Group Inc.’s Scott Rubner, who has studied the flow of funds for two decades. With indexes such as the S&P 500 breaking below key thresholds, trend-chasing systematic funds are at risk of being forced to unwind equity holdings.

By his estimate, commodity trading advisers that surf the momentum of asset prices through long and short bets in the futures market will unload $48 billion of global stocks over ...