So much for the idea that Federal Reserve Chairman Kevin Warsh's speeches will be a nonevent. The central bank chief insists he doesn't give forward guidance but markets think his presentation at a monetary-policy conference was a clear sign of higher interest rates and a test ahead for technology stocks.

Warsh was having fun when he mentioned the word "hike" three times in the first couple of minutes of his speech-in the trekking sense rather than raising rates. But his subsequent comments about "65 months" of sustained inflation and the Federal Reserve's responsibility to tackle seemed more serious.

Traders think they got the hint and now see the chances of a September interest-rate increase at more than 60%, according to the CME FedWatch tool, up from less than 50% before Warsh's appearance.

Those percentages still indicate substantial uncertainty. Markets are waiting on Friday's jobs report this week to get a clearer picture of the strength of the labor market. Investors also have to digest rising oil prices after American forces carried out their first strike in weeks on the Iranian military over the weekend, balancing that against evidence that crude is flowing in the Persian Gulf. But the momentum is with those arguing for higher rates right now.

The prospect of higher borrowing costs poses an obstacle for the AI trade and technology stocks more generally. The momentum trade-which was dominated by buzzy chip stocks-has gone into reverse amid fears about the sustainability of huge capital expenditures. That could mean there's a high bar for earnings from Broadcom, Dell Technologies, and Ciena this week-all AI infrastructure plays that have been notably weak in recent months.

September is historically the worst month for stocks and Warsh's comments suggest economic conditions are due for a change. Fall could bring tougher times for the tech trade.