A type of financing that peaked before credit markets seized up four years ago is staging a comeback just as concern mounts that corporate profits are falling and the global economy is losing steam.

Offerings of $2.1 billion in the past 30 days of so-called payment-in-kind notes, which allow borrowers to pay interest with extra debt, account for more than a third of this year's $6 billion of deals, according to data compiled by Bloomberg. Pharmaceutical Product Development Inc., a Wilmington, North Carolina-based contract research firm, sold $525 million of the notes yesterday.

Sales of high-yield, high-risk bonds are soaring to a record pace as interest rates hover at unprecedented lows send investors toward riskier assets. JPMorgan Chase & Co. says credit metrics are deteriorating, with leverage at investment-grade borrowers potentially approaching financial crisis levels by year-end, as the International Monetary Fund lowers its global growth forecast to the slowest pace since 2009.