JPMorgan's AI agents beat traditional stock/bond mix in backtests—but proof is missing

JPMorgan says eight AI agents outperformed a 60/40 portfolio (60% stocks, 40% bonds) when tested on past data. But the bank didn't publish costs, how much they traded, or whether the AI would actually work going forward. Beating yesterday's markets is easy. Actually predicting tomorrow is harder—and JPMorgan hasn't shown that evidence yet.