Blue-chip companies that need to borrow in the U.S. are increasingly relying on commercial paper to avoid locking in longer-term borrowing costs in a market beset by turbulence.

With the Federal Reserve poised for a fresh interest-rate hike later today, the days when blue-chip firms could borrow super-cheaply for decades are gone, at least for now. Corporate treasurers have instead been turning more to commercial paper, a type of unsecured debt that typically lasts 270 days or less.

The total volume of these IOUs outstanding has mushroomed to nearly $1.2 trillion this year, up more than 20 percent from its lows in 2020, with computing giant Apple Inc. and pipeline-owner Kinder Morgan Inc. among those that have been dipping more into the market this year. At the same time, investment-grade companies are relying less on longer-term debt markets, with sales of high-grade corporate bonds dropping about 7 percent in 2022, according to data compiled by Bloomberg.