The global benchmark is dominated by U.S. high-yield bonds, which have been buoyed by the Federal Reserve’s ultra-easy monetary policy and a robust economic recovery. Energy producers, a large slice of the U.S. market, have also benefited from a surge in commodity prices. As of Friday, the equivalent U.S. index yielded 4.65%.

The divergence means that Chinese junk bonds yield 5.36 percentage points over the global index. Apart from a brief period in March 2020, this spread, or gap, hasn’t been above that level since early 2012, ICE BofA data shows.

China’s policy makers, who once favored bailouts, have grown more tolerant of defaults in recent years. Authorities remain wary of market turbulence, but also want to restrain debt growth, and to dispel the idea that investors will always be made whole.

The balance sheets of most U.S. junk-bond issuers are improving, said Freddy Wong, head of the Asia-Pacific region for Invesco’s fixed-income business. In contrast, he said, investors were bracing for selected Chinese real-estate developers to run into financial trouble.

Property companies make up a large portion of the Chinese junk bond market. Major borrowers that have had difficulties recently include industrial-park specialist

China Fortune Land Development Co.

, which defaulted earlier this year, and

China Evergrande Group,

a major residential developer whose shares and bonds have sold off recently.

China’s largest distressed-asset manager, China Huarong Asset Management Co., has also shaken investor confidence by delaying the release of its financial results. Huarong has been a major investment-grade borrower in international markets.

A tightening credit cycle had exposed the financial weaknesses of some developers who had borrowed aggressively, said Mr. Wong of Invesco. In some cases, poor transparency had also hurt investor appetite, he said.

To be sure, for some investors, the extra return available on lower-rated Chinese debt more than makes up for the extra risks. Chinese real-estate firms have been able to sell large quantities of dollar-denominated debt this year.

Chinese junk bonds are underperforming regional peers this year, such as similar debt from India and Indonesia, said Kenneth Ho, head of Asia credit strategy research at Goldman Sachs.

Mr. Ho said yields on Chinese junk bonds were likely to stay high, and investors were likely to focus on trying to minimize their risks rather than maximizing returns. He said this meant they would probably seek to buy debt from a few specific borrowers that they know well, rather than investing broadly.

“Once we see signs of deleveraging from earnings reports and see idiosyncratic risks subside, then maybe valuations will get more people attracted to the market,” he said.

Write to Frances Yoon at frances.yoon@wsj.com