Powell has never responded directly to Trump's provocations, and I, personally, expect this issue to play a predominant role at his latest meeting in Jackson Hole, perhaps even more so than the interest rate discussion. The independence of central banks is much more important than a 25 basis point change in the coming month.

Financial markets are taking in a collective breath ahead of Jerome Powell's eighth and final keynote Jackson Hole speech as Federal Reserve Chair. If the moves following his last seven are any guide,

This week's set-piece event is the Jackson Hole central-bank gathering in Wyoming, slated for Thursday through Saturday. Investors will tune into Federal Reserve Chair Jerome Powell's speech for any hints on whether the central bank might kick off interest-rate cuts in September.