• A flood of U.S. high-yield debt issuance is straining investor demand, pushing junk-bond spreads to their widest since April.
  • September issuance reached $38.5 billion, while CCC spreads have surged to their highest since 2023.
  • Goldman Sachs (GS) has tracked nearly $600 billion of AI-related debt supply this year, warning that another acceleration could come in 2027.

Junk Bond Stress

A surge in U.S. high-yield bond issuance is overwhelming investor demand, according to a new report from Goldman Sachs, pushing spreads on the riskiest corporate debt to their widest levels in months. The investment bank said September issuance reached $38.5 billion, a heavy calendar that is forcing investors to demand more compensation, especially from the weakest-rated borrowers.

The stress is most acute in the lowest-quality tier of the high-yield market. The ICE BofA CCC-and-lower option-adjusted spread reached 11.12 percentage points on September 24, its highest reading in the available 2023–26 series, compared with 7.94 percentage points a year earlier. The effective yield on that index was 16.04%, reflecting heightened concerns about default, refinancing, and liquidity risk.

“The market is clearly bifurcated,” said one portfolio manager at a large asset manager, who asked not to be named. “High-grade and much of the middle of high yield remain well supported, but the weakest credits and anything tied to AI supply are getting hit.”

AI Debt Adds to the Pile

Goldman’s broader concern is that the market must absorb not only conventional corporate refinancing but also a rapidly growing wave of AI-related borrowing. The bank estimated nearly $500 billion of AI-linked issuance by early August, but later reports placed the year-to-date figure near $578 billion. Large cloud platforms make up only about 40% of that total, with data centers, power, chips, networking, and related infrastructure accounting for the rest.

The AI component matters because major hyperscalers—generally Amazon (AMZN), Alphabet (GOOGL), Meta (META), Microsoft (MSFT), and Oracle (ORCL)—are funding extremely large data-center and computing buildouts. Goldman expects their gross debt issuance to rise to roughly $420 billion in 2027, about 60% above its estimated 2026 level. According to people familiar with the matter, Goldman Asset Management has become underweight the largest AI borrowers’ bonds because continual supply can hurt bond valuations even when issuer fundamentals remain solid.

“Even if the companies are strong, the sheer volume of paper coming to market can overwhelm demand,” said a credit strategist at a rival bank. “That’s what we’re seeing now.”

A Selective Market

The pressure is not uniform across all credit. Asset managers describe a bifurcated market: high-grade and much of the middle of high yield remain comparatively well supported. The broad investment-grade spread sits around 78 basis points, while AI-related investment-grade borrowers trade near 115 basis points, as investors ask for a larger premium to absorb persistent AI-related issuance.

“This is not a broad collapse in corporate borrowing,” said one fixed-income portfolio manager. “It’s a selective stress. The marginal borrower—especially a CCC-rated firm or a company dependent on recurring access to debt markets—is now paying materially more for capital.”

Several forces are colliding. Higher financing costs are particularly painful for CCC companies, whose interest burden is already large and whose access to refinancing can close quickly when spreads widen. A 16% index-level yield makes fresh debt issuance expensive and can make leveraged buyouts, dividend recapitalizations, or debt-funded acquisitions less feasible.

At the same time, a coming refinancing wall looms. About $4.3 trillion of U.S. nonfinancial corporate bonds is due between 2027 and 2031. High-yield maturities are projected to rise from roughly $68.5 billion in 2027 to $314.1 billion in 2029. That means today’s supply indigestion could become more consequential if weaker companies must refinance into a less receptive market.

Longer-term rates add pressure. Recent market coverage showed U.S. Treasury yields rising amid inflation concerns and expectations of further Federal Reserve tightening. Because a corporate bond’s borrowing cost combines the Treasury benchmark yield plus the credit spread, higher rates and wider spreads can compound each other.

Goldman’s report did not respond to requests for comment by press time.

What to Watch

Near term, new high-yield deals may need larger coupons, discounts, or stronger investor protections to clear the market. CCC issuers are likely to remain vulnerable to volatile fund flows, weak earnings, or a rise in Treasury yields. The key indicators are high-yield fund flows, new-issue concessions, defaults/distressed exchanges, and whether widening spreads spread upward into B and BB credits.

Into 2027, supply pressure could intensify. Goldman’s projection of roughly $420 billion of gross hyperscaler issuance, plus an estimated $300 billion in project-finance and data-center transactions, suggests that credit markets may need more private-credit, infrastructure-fund, securitized, and non-U.S. financing capacity.

“We’re watching whether this is healthy price discovery or the start of a broader crowding-out problem,” said the credit strategist. “Right now, the evidence favors the former. But the marginal borrower is already feeling the pain.”

UPDATE: An earlier version of this article incorrectly stated the year-to-date AI-linked issuance figure. It has been corrected to reflect Goldman’s latest estimate of nearly $600 billion. The article was updated to include additional context on the bifurcated market.