An investor looks over his shoulder as he monitors screens showing stock information, at a brokerage house in Hefei, in China's Anhui province.

Shanghai - As a rout in Chinese stocks this year erased $5 trillion of value, investors fled for safety in the nation’s red-hot corporate bond market. They may have just moved from one bubble to another.

So says Commerzbank, which puts the chance of a crash by year-end at 20 percent, up from almost zero in June. Industrial Securities and Huachuang Securities are warning of an unsustainable rally after bond prices climbed to six-year highs and issuance jumped to a record. The boom contrasts with caution elsewhere. A selloff in global corporate notes has pushed yields to a 21-month high, and credit-derivatives traders are demanding near the most in two years to insure against losses on Chinese government securities.

While an imminent collapse isn’t yet the base-case scenario for most forecasters, China’s 42.2 trillion yuan ($6.7 trillion) bond market is flashing the same danger signs that triggered a tumble in stocks four months ago: stretched valuations, a surge in investor leverage and shrinking corporate profits. A reversal would add to challenges facing China’s ruling Communist Party, which has struggled to contain volatility in financial markets amid the deepest economic slowdown since 1990.

“The Chinese government is caught between a rock and hard place," said Zhou Hao, a senior economist in Singapore at Commerzbank, Germany’s second-largest lender. "If it doesn’t intervene, the bond market will actually become a bubble. And if it does, the market could crash the way the equity market did due to fast de-leveraging.”

The slide in stocks is one reason why corporate bonds have done so well, prompting a 91 percent jump in issuance last quarter. Many investors who sold shares during the Shanghai Composite Index’s 38.4 percent drop from its June high have plowed the proceeds into debt, viewing the market as a haven given its history of almost negligible defaults. Five interest-rate cuts since November have also fueled gains as the People’s Bank of China seeks to revive growth with lower borrowing costs.

Yields on top-rated corporate notes due in five years have declined 79 basis points, or 0.79 percentage point, this year to 4.01 percent. The yield premium over similar-maturity government securities has dropped to 97 basis points, near the lowest since 2009.

By contrast, the yield on corporate notes globally has increased 26 basis points to 2.92 percent. Credit-default swaps on China’s sovereign debt jumped to a more than two-year high of 133 basis points in September and were last at 113 basis points.

Risks rise

A reversal in the bond market would do more damage to China’s economy than the drop in shares and exacerbate capital flight from the biggest emerging market, according to a worst- case scenario projected by Banco Bilbao Vizcaya Argentaria. The Spanish lender more than doubled its first-quarter profit by selling holdings in a Chinese bank.

“The equity rout merely reflects worries about China’s economy, while a bond market crash would mean the worries have become a reality as corporate debts go unpaid," said Xia Le, the chief economist for Asia at Banco Bilbao. "A Chinese credit collapse would also likely spark a more significant selloff in emerging-market assets.”

For all the concerns about a bond rout, default levels in China have so far been remarkably low, thanks in part to government-orchestrated bailouts for troubled firms. Just four companies have defaulted on onshore bonds, including Shanghai Chaori Solar Energy Science & Technology, which became the first to renege on its debt in 2014.

Government firepower

China has the wherewithal to stave off a crisis in its credit markets, according to Ken Hu, chief investment officer for Asia-Pacific fixed income at Invesco. "Unlike most other emerging-market countries, China has high domestic saving rates, little government debt, healthy fiscal balances, strong trade and current account surpluses, and most of its corporate debts are domestic," he said.

Policy makers went to unprecedented lengths to combat the tumble in share prices, including compelling state-owned firms to buy equities and preventing major stockholders from selling. The Shanghai Composite rose 1.27 percent on Friday, its second straight day of advance after a week-long national holiday.

A recovery in the equity market could be the trigger for a selloff in bonds as money managers liquidate their holdings to catch the rally in stocks, according to Thomas Kwan, the Hong Kong-based chief investment officer at Harvest Global Investments, whose Chinese unit offers funds through the Qualified Domestic Institutional Investor program.

Warning signs

The risk of a downward spiral in debt prices has increased after investors took on leverage to amplify their returns, according to Ping An Securities. The monthly volume of bond repurchase agreements - a form of borrowing used by investors to increase their buying power - has jumped 83 percent from January to 39 trillion yuan in September, according to data from the Chinamoney website.

About 16 percent of companies on the Shanghai stock exchange lost money in the past 12 months, double the proportion last year, and the number of firms with debt levels twice their equity has doubled to 347 since 2007. Profits at Chinese industrial companies sank 8.8 percent in August from a year earlier, the biggest decline since the government began releasing monthly data in 2011.

Baoding Tianwei Yingli New Energy Resources, a maker of solar components, could become the latest Chinese company to default on local-currency notes after its parent said it’s unlikely to meet a deadline next week on a 1 billion yuan bond.

“Global investors are looking for signs of a collapse in China, which itself could increase the chances of a crash,” Commerzbank’s Zhou said. “This game can’t go on forever."