US companies issued $57 billion in convertible bonds in 2026 through the comparable period — the highest on record for that stretch, according to Barclays Research. The surge reflects AI infrastructure spending reviving a corner of the debt market that hadn't seen these volumes since the early pandemic.

Total convertible bonds outstanding crossed $300 billion for the first time since COVID-19, per FactSet data published December 2025, with global issuance running at a 24-year high as of January 2026. By June, market volume had reached its highest level since the pandemic started. The trend had actually been building for quarters — deals hit a five-year high as early as September 2025.

How Convertibles Work

A convertible bond is part debt, part equity option. It pays interest like a regular bond, but gives the bondholder the right to convert it into company stock at a preset price. This setup benefits both parties. The issuer gets to pay a lower interest rate than it would on plain debt because investors gain upside if the stock rises. For CFOs funding capital-intensive projects like AI datacenters — which demand spending now but may or may not pay off later — that lower cash interest burden is valuable.

The math changes when interest rates rise. After years of near-zero rates, the gap between what convertibles cost versus straight debt has widened. That makes the equity dilution risk — the possibility of issuing new shares when bonds convert — an acceptable trade-off, especially for companies whose stock prices have already risen on AI optimism.

Alibaba shows the pattern. The company raised $5 billion via convertible bond in May 2024, then $1.5 billion through an exchangeable bond in July 2025, and announced a $3.2 billion convertible offering in September 2025 specifically for cloud growth. Three financing transactions in 16 months using the same instrument signals methodical capital matching, not financial stress.

The Bigger Picture

The $57 billion figure rests on a trajectory that was already accelerating. LSEG data from April 2024 showed over $20 billion issued in the US in Q1 2024 alone, with $26 billion globally. The acceleration since — past $300 billion outstanding, past 24-year records — reflects both the scale of AI capital spending ambitions and the market's willingness to absorb volume.

Context matters. Convertible markets were largely quiet through the 2010s when normal investment-grade debt was cheap; the complexity of a convertible structure offered no advantage. The 2022 rate reset changed that. Higher base rates mean higher coupons on straight debt, which makes the interest-rate subsidy built into convertibles more valuable. This reopening is simultaneously a rate story and a technology capex story.

The structural bid from convertible arbitrage funds — investors who buy the bonds and short the underlying stock to isolate the embedded option — does have limits. If issuance pace in 2026 pushes volumes faster than arbitrage capital can absorb, pricing may deteriorate: spreads could widen and deal terms turn less favorable. That would signal the natural buyer base is near capacity.

When a technology wave demands heavy front-loaded spending against genuine but unresolved equity upside, convertibles fit naturally. AI infrastructure has that profile: capital-intensive now, with an embedded equity option that investors are pricing generously. Whether those conversion premiums prove justified depends on how quickly — and profitably — companies actually monetize the AI they're building. The bond market is pricing optimism. The actual earnings still have to show up.