“It’s pretty clear that human beings aren’t improving,” said Spencer Greenberg, 27 years old and the brains behind Rebellion’s AI system. “But computers and algorithms are only getting faster and more robust.”

Savor that for a moment. But wait! There’s more:

The firm’s current portfolio is largely defensive. One of its biggest positions is in gold stocks, according to people familiar with the fund.

The defensive move at first worried Mr. Fleiss, who had grown bullish. But it has proven a smart move so far. “I’ve learned not to question the AI,” he said.

Letting the Machines Decide: New Wave of Investment Firms Look to ‘Artificial Intelligence’ in Trade Decisions