Charted: HS Senior Alone Is ~49% of Funded AI Credit — Top-3 Channels Clear 91%

Our theme already maps the vintage path. The July research put hyperscalers on a Goldman path toward ~$250B / ~33% of AI capex funded with IG bonds. The mid-year update answered the theme perimeter question: AI-related debt near $489B, with the five names only ~40% of that stack. The late-Aug concentration companion scored issuer Top-1 / Top-3 on the Aug YTD spine (~$194B, Amazon ~41% / top-3 ~76%). The Q3 concentration refresh re-asked the same question as issuance grew toward mid-Q3. The August stock-map update then replaced the flow-only perimeter with a Booth/Hepp funded channel stock near $1.065T. This post answers the distribution question on that stock-map spine: how concentrated is the system at the top once outstanding claims — not just YTD prints — define the denominator?

The interactive dashboard above is built as an August 202608 concentration lens. Toggle Credit channels, Issuer ladder, Commitment + stress, and ETF + lenses. The punchline is deliberately multi-sided. On funded channels, HS senior unsecured alone is about 49% of ~$1.065T and the top-3 channels clear ~91%. On issuers, Amazon still leads the carried Aug flow spine at ~41% / top-3 ~76%. On total commitment, uncommenced leases (~$675B) are about 39% of funded-plus-overhang — a second concentration meter the flow lens never saw. On equity flows, QQQ still takes roughly half of 2025 thematic ETF inflows. Same theme, four different tops — with the stock map as the primary spine.

The August concentration scoreboard

Read the table as a family of market shares, not one slogan. Channel-stock concentration is the August headline: nearly half the funded map sits in one senior sleeve, and three channels clear nine-tenths. Issuer concentration inside the hyperscaler cohort remains thick on the carried Aug ladder. Theme-stack concentration is milder once utilities, DC JVs, and ecosystem credit enter the perimeter. Lease overhang is a commitment story, not an issuer story — but it is still a Top-1 meter on a larger denominator. ETF concentration is a sentiment-capacity story. Analysts who quote only “hyperscalers are 40% of AI debt” understate how top-heavy the funded channel stock is; analysts who quote only Amazon megadeals understate how much of the build now sits in project, private, and off-balance sleeves.

Credit channels: senior IG is half the funded map

Open Credit channels. The Booth/Hepp stock map from our August 202608 update puts funded AI-infra credit near $1.065T. HS senior unsecured alone is about $520B / 49%. Project / data-centre finance (~$250B / 23%) and private credit (~$200B / 19%) push the top-3 channel share to ~91%. ABS (~$60B / 6%) and GPU-secured (~$35B / 3%) are thin residuals. Approximate channel HHI on five buckets sits near 3,280 — well above the issuer HHI on the five-name flow ladder (~2,470).

This is a different concentration story from issuer YTD flow. Flow asks who printed paper this year. Channel stock asks where the outstanding claims sit. A market can look diversified on monthly deal tapes while the stock remains dominated by senior unsecured held by funds, insurers, and pensions. Conversely, private credit and project finance can dominate the narrative without yet matching the senior sleeve’s stock weight.

The seniority panel underneath re-buckets the same map: senior (HS IG + ABS) ~54%, hybrid (project/DC) ~23%, junior (private + GPU) ~22%. Senior sleeves hold the majority of stock; junior sleeves hold a minority of stock but — in the stress incidence scatter — a disproportionate share of first-loss weight. That asymmetry is the August stock-map contribution the late-Aug issuer companion could only flag in a footnote.

Issuer ladder: Amazon still owns the thick end of the flow spine

Filter the dashboard to Issuer ladder. The stock-map vintage does not rewrite the Aug YTD five-name universe (~$194B). Cumulative share still rises to about 41% at top-1, 61% at top-2, and 76% at top-3. Amazon’s disclosed multi-tranche USD/EUR prints make it the modal top-1; Alphabet and Meta fill the next rungs; Oracle’s releveraging path and Microsoft’s still-OCF-heavy posture close the ladder.

The Aug → Q3 → FY path panel shows how that tip eases as the spine grows: mid-Q3 (~$218B) prints top-1 nearer 39% and top-3 nearer 74% as peers catch up toward the ~$250B FY path. Absolute issuance rises; inside-cohort concentration softens at the margin. That is the opposite of the channel-stock story, where the senior sleeve’s stock weight stays extreme even when monthly deal counts look plural.

Pair this panel with the research post’s funding-mix story: debt is still only about a third of hyperscaler capex on Goldman’s path. Concentration of issuance can coexist with concentration of cash-flow funding — Amazon can dominate the bond calendar while the cohort as a whole still funds the majority of servers from operating cash flow. Our AI capex spend concentration lens tracks the spend side of that coin.

Theme stack and calendar weight: thick inside, minority outside

Of the mid-year AI-related debt perimeter (~$489B), hyperscaler IG is about $194B / 40% and the broader ecosystem is about $295B / 60%. The five-name bloc is concentrated internally (top-1 ~41%) but is still a minority of the theme once utilities, industrials, data-centre JVs, HY, and loans enter the tally.

That hinge — thick inside, minority outside — is why the stock-map concentration post leads with channels rather than issuers. The flow perimeter still says the five names are 40% of AI debt. The funded map says one channel (HS senior) is nearly half of outstanding AI-infra credit claims. Both can be true. Desks that underwrite “AI credit = Mag 7 bonds” are reading the thick end of a minority sleeve of the flow tape and the majority sleeve of the stock tape at the same time.

The supply-path panel shows calendar concentration rising even when issuer ladders stay sticky: AI’s share of US IG gross supply climbed from ~1% in 2024 to ~7% in 2025, ~18% at the August desk print, and ~23% in the Q3 refresh — with HY near 20%. Theme weight inside the calendar can concentrate without any single issuer matching Amazon’s inside-cohort share.

Commitment + stress: leases and first-loss asymmetry

Toggle Commitment + stress. Uncommenced leases (~$675B, S&P disclosed) sit outside funded totals by design. Fold them into a total-commitment universe (~$1.74T) and leases alone are about 39% — a Top-1 meter on a different denominator. The analytical mistake is either to ignore the overhang (understating committed AI-infra exposure) or to fold it into funded Top-1/Top-3 prints (mixing off-balance commitments with outstanding claims).

The stress-incidence scatter is an editorial mix, not a cite-ready loss allocation. Booth’s illustrative band puts credit losses near $60–140B against a $10–14T equity re-rating. In this mix, junior sleeves (private + GPU, including the Anthropic/Apollo–Blackstone ~$35B GPU SPV tip) punch above their funded weight on first-loss share, while senior IG absorbs a smaller loss share than its 54% stock weight. That is the risk-distribution cousin of the concentration question: the system is concentrated in senior stock and concentrated in junior first-loss at the same time.

ETF flows: half the thematic sleeve is one ticker

Toggle ETF + lenses. FactSet’s 2025 US thematic ETF inflow sleeve was about $43.5B. QQQ alone absorbed ~$21.7B — roughly 50%. Semiconductor proxies (SOXX-scale) add another ~20%; narrow robotics/AI thematics remain a thin wedge; the residual thematic sleeve fills the last quarter.

Equity-side concentration is a sentiment-capacity meter. Creations into QQQ are not issuer proceeds for Amazon’s data centres; they are secondary ownership of a Mag 7–heavy Nasdaq-100 proxy. Still, for the theme’s public-markets question — how is the build-out funded in credit and public markets? — the answer is asymmetric. Credit funding concentrates in a handful of IG issuers and a senior channel stock. Equity flow concentration concentrates in one broad proxy that prices the same names.

The cross-lens scatter makes the asymmetry visual: channel stock sits upper-right (Top-1 ~49% / Top-3 ~91%); issuer and ETF lenses sit high on both axes; the AI-debt bloc, IG-calendar, and lease-commitment lenses are high on top-1 but lack a meaningful top-3 ladder because they are single-bloc / theme prints.

Who is exposed — and what would change the story

Exposed: IG portfolios that treat “AI-infra credit” as diversified across five channels when three clear ~91% of funded stock; desks that size theme risk off the $489B flow perimeter without noticing the $520B senior sleeve inside the stock map; insurers and pensions whose AI-infra exposure is mostly the senior unsecured book and therefore inherit issuer-ladder concentration whether or not they own project-finance paper; equity allocators who read thematic ETF creations as diversified AI exposure when half the sleeve is QQQ; risk books that ignore the $675B lease overhang because it is off-balance.

Relative winners under current rules: mega-issuers that can still clear multi-tranche books inside AA/A technicals; intermediaries that intermediate the overflow into project finance and private credit as IG calendars saturate; holders of the senior unsecured sleeve while lease overhang and GPU-secured risk sit elsewhere in the capital stack; broad-proxy ETF complexes that capture Mag 7 ownership demand without needing narrow AI wrappers.

What would change the story: a funded-stock mix where project + private credit displace HS senior below ~35% of the map; a sustained flattening of the issuer ladder so top-1 falls below ~25% of hyperscaler IG; ecosystem debt growing so fast that the HS bloc share of the AI perimeter falls well below 30% and issuer concentration inside the bloc breaks; lease overhang converting into funded stock without raising senior concentration further; thematic ETF flows dispersing so no single ticker holds more than ~30% of the sleeve. None of those appear as the central print in the Aug 202608 stock-map vintage.

Caveats and methodology

• Channel stock (~$1.065T) is a research synthesis (Booth/Hepp Aug 7 2026 map); private-credit and some project sleeves are estimated and can overlap deal tallies.
• Issuer shares inside the five-name YTD spine are estimated from disclosed Reuters/LSEG deal prints and close to the Goldman ~$194B total. Treat top-1 / top-3 as order-of-magnitude concentration, not a prospectus table.
• AI debt perimeter (~$489B) mixes IG, HY, loans, and ecosystem credit; the 40% HS share is a bloc share, not an issuer ladder.
• IG/HY calendar weights (~23% / ~20%) are theme shares of gross supplynot top-1 issuer shares of the calendar.
• Uncommenced leases (~$675B) are disclosed (S&P) but excluded from funded-stock concentration by design; the 39% commitment share uses a simple funded+leases denominator.
• Stress incidence is an illustrative editorial mix scaled to the Booth $60–140B bandnot a cite-ready loss allocation by channel.
• ETF flows are net creations, not AUM, and QQQ is a Mag 7 proxy rather than a pure AI product.
• Equity raises (e.g. Alphabet’s mid-2026 ~$85B print) are excluded from the IG issuer ladder on purposethey concentrate funding without concentrating bond supply.
• GPU SPV tip (~$35B) sits inside the GPU-secured sleeve; treat it as a specialist tip, not a parallel of the HS senior sleeve.

The shareable takeaway

AI financing is concentrated at the top — but which top depends on the meter. On the August 202608 stock-map spine, top-1 (HS senior unsecured) is about 49% of funded credit and top-3 channels clear about 91%. Inside hyperscaler IG flow, top-1 (Amazon) is about 41% and top-3 about 76%. Of the $489B AI debt perimeter, the five-name bloc is still only ~40%. Of total commitment, uncommenced leases alone are ~39%. Of thematic ETF inflows, QQQ takes ~50%. The build-out is funded in credit and public markets through a system that looks diversified in press-release counts and top-heavy once you rank the distribution — especially once outstanding claims replace YTD flow as the denominator.

Related reading: Aug 202608 stock-map update · Late-Aug concentration companion · Q3 concentration refresh · AI financing research 2026.