The odds of a Fed rate hike in September are running near a coin flip, keeping investors on edge until next week's inflation report.

• Taiwan's central bank puts the market-implied chance of a September hike at about 50%, with hawks and doves on the Fed roughly evenly split.
• Fed governor Christopher Waller has signaled he would leave rates alone if August inflation keeps moving toward 2%, but would consider a hike if prices jump unexpectedly.
• The August consumer price report lands days before the Fed's meeting, making it the deciding piece of data.
• US inflation is still falling, but the worry has shifted to whether it is falling fast enough — core inflation is stuck near 2.4%.
• Economic data has barely changed since the Fed's July meeting, so the inflation number carries outsized weight.

Outlook: A tame CPI would push hike odds lower, while a hot number would tilt the Fed back toward raising rates.