Bond traders are pricing in a Federal Reserve interest-rate hike Wednesday with a level of conviction that has proven right for decades. Interest-rate swaps tied to Fed meeting dates show traders see more than a 90% chance that Fed Chairman Kevin Warsh and his colleagues will lift the benchmark policy rate by a quarter point from the current 3.5%-3.75% range. That equates to roughly 23 basis points of tightening priced in.

Whenever expectations of a hike have been that high, the Fed has invariably delivered it, according to Bloomberg-compiled data going back to 2008. Of course, the setup for this decision has an unusual backdrop, given that President Donald Trump, who picked Warsh, repeatedly pressed the central bank to slash rates under former chief Jerome Powell. The market is not prepared for a hold or dovish hike, said Caesar Maasry, head of investment research at Lunate.

The Fed has historically sought to avoid surprising markets, particularly when raising rates, given the risk of triggering volatility. But uncertainty around its decisions has increased since Warsh took the helm in May and abandoned the Fed’s long-held practice of signaling policy moves well in advance. That was evident in late July, when traders saw a 38% chance of a rate increase the day of the decision, before the Fed ultimately stayed on hold.

At the July gathering, Warsh’s ambiguity on his plan to fight inflation helped trigger a selloff in long-term bonds. This time, however, the level of confidence is much higher. Expectations for a September hike began building after Warsh said last month that the Fed would ensure that inflation will cool “at sufficient speed.” By Friday, traders all but locked in an increase after consumer-price data showed inflation — which has remained above the Fed’s target for more than five years — was showing little sign of cooling.

After the report, a slew of major Wall Street firms changed their September calls from a hold to a quarter-point increase. Wednesday’s announcement comes as a global bond rout has pushed the 10-year Treasury yield to the highest since 2007, with surging oil prices fueling inflation concerns. Tomorrow’s Fed will be the most consequential one we’ve had in some time, said Alex Cohen, a foreign-exchange strategist at Bank of America.

With a hike about 90% priced, it would be nearly unprecedented for them to hold at this stage.