Just a day after Federal Reserve policymakers delivered their biggest rate hike in 28 years, the US inflation outlook continues to look dire in one obscure part of the financial market.

Traders of so-called fixings, or derivatives-like instruments related to Treasury inflation-protected securities, expect four straight months of annual headline consumer price index readings at roughly 9% or higher from June through September. That would be the longest stretch of such elevated readings since 1981 — the same year that the Fed, led by Paul Volcker, was forced to push the fed-funds rate target to as high as 20%, according to FactSet data. The outlook for a roughly 9% September CPI rate has been in place since May’s CPI report was released on 10 June, one trader said.