Stephen Mandel's Q1 2026 13F moves
TL;DR
Lone Pine Capital's Q1 2026 13F-HR (filed 2026-05-15) shows Stephen Mandel making one of the cleaner thematic bets this quarter: the physical infrastructure of AI. The top holding is Vistra (7.4%), and Talen Energy was added 41% — two independent power producers positioned for datacenter electricity demand. Around them sits a semiconductor-equipment, materials and construction sleeve: ASML (+8%), Carpenter Technology (+38%), and brand-new positions in Teradyne, Corning and MasTec. AppLovin was added 88%. Funding it, he trimmed TSMC by 54% and Brookfield by 37%. Every move is reconstructable from EDGAR using Form 13F-HR.
The Q1 2026 picture
Lone Pine is a long-only growth fund — Mandel founded it in 1997 after Tiger Management, and it has compounded quietly into one of the most successful growth books of the last three decades. At 36 positions it is concentrated enough that the top names carry a real thesis. In Q1 2026 that thesis is unusually legible: rather than owning the AI chips directly, Lone Pine bought the power and the plumbing that AI compute depends on.
The AI-power bet (the headline)
- Vistra (VST) — the top holding at 7.4%, added 19%. An independent power producer whose nuclear and gas fleet is a direct play on datacenter electricity demand.
- Talen Energy (TLN) — added 41% to 4.6%. Another independent power producer, well-known for datacenter power-supply agreements. Two of the top holdings are now merchant-power names.
Equipment, materials + construction (the plumbing)
- ASML — added 8% to 6.9%, the #2 position. The lithography monopoly that every advanced chip depends on.
- Carpenter Technology (CRS) +38% to 5.7% — specialty alloys for aerospace and industrial demand.
- Teradyne (TER), Corning (GLW), MasTec (MTZ) — all brand-new positions (~4% each): semiconductor test equipment, optical-fibre and materials, and infrastructure construction. Together with Clean Harbors (+27%), this is a deliberate real-economy-infrastructure cluster.
Other adds + the funding trims
- AppLovin (APP) +88% to 4.6%, Nu Holdings (NU) +28%, Tenet Healthcare (THC) +26%; new US Foods. Growth names added outside the infrastructure theme.
- TSMC (TSM) −54%, Brookfield (BN) −37% — the largest reductions. Notably, he cut the foundry (TSMC) while adding the equipment maker (ASML) and the test-equipment maker (Teradyne).
What the pattern signals
The thesis is own the infrastructure of AI, not the chips. Power producers (Vistra, Talen), semiconductor equipment (ASML, Teradyne), materials (Corning, Carpenter) and construction (MasTec) all gained weight, while the chip foundry (TSMC) was halved. It is a bet that the bottleneck — and the durable margin — in the AI build-out is electricity, equipment and materials rather than the leading-edge silicon itself.
The 13F alone cannot tell us why, and Lone Pine's 13F shows only the long book. But the direction is unusually coherent for a 36-name fund: a concentrated tilt toward the physical supply chain of compute.
For comparison, this quarter's recaps show the AI trade expressed many ways. Chase Coleman bought the chips and equipment directly (Nvidia, TSMC, Applied Materials). Andreas Halvorsen tilted toward quality industrials. Mandel went one layer further down — into the power and plumbing. Same macro theme, materially different expressions, all in the public EDGAR record.
How to verify this yourself
Every position change above is reconstructable from public SEC EDGAR filings. Steps:
- Open Lone Pine Capital's 13F-HR filing history on EDGAR (CIK 0001061165).
- Compare the Q1 2026 13F (filed 2026-05-15, report date 2026-03-31) line-by-line against the Q4 2025 13F (filed Feb 2026).
- Position changes appear as: increased share counts (Vistra, Talen, ASML, Carpenter, AppLovin adds), decreased share counts (the TSMC and Brookfield trims), and new CUSIP rows (Teradyne, Corning, MasTec, US Foods).
- Cross-reference with HoldLens's machine-readable /api/v1/snapshot/2026-Q1.json and the live Stephen Mandel portfolio page.
Our view
Six historical trades reconstructable from SEC EDGAR alone. Each essay traces the trade through 13F + Form 4 + DEF 14A filings.
Berkshire's 1988-89 KO purchase — $1.3B → ~$28B, untouched 37 years.
Berkshire's 2016-onward AAPL accumulation — largest equity position in firm history.
The $5B preferred + 700M-share warrants at $7.14 strike. ~$13B paper gain at 2017 exercise.
Appaloosa's $2B March 2009 distressed-bank bet (BAC + C + AIG). ~$7B returned. $4B Tepper payday.
Scion Capital's 2005-2008 subprime CDS trade — ~489% net return.
Pershing Square's 2012-2018 multi-year activist campaign.
September 16, 1992. The single-day macro trade that broke the Bank of England.
1997-2023 hold + board seat — the canonical long-duration value position.
2013-2016 long-side activism — public letter to Tim Cook, ~$2B realized gain.
Cite this page
Researchers, journalists, and Wikipedia editors — citation formats load with the page. HoldLens content is freely available for reference; please cite.
Recommended reading
The six books that map the mental model behind every 13F on this site.
Amazon affiliate links — as an Amazon Associate, HoldLens earns from qualifying purchases at no extra cost to you. These are the books we actually recommend. Always do your own research.
Every tracked manager's Q1 2026 moves + top consensus positions, in one place.
Every position, ConvictionScore, and quarter-over-quarter change — live, SEC-sourced.
Not investment advice. Sourced from public SEC EDGAR Form 13F-HR filings (Lone Pine Capital CIK 0001061165). All position changes verifiable from Form 13F-HR alone. A 13F shows only long U.S.-listed positions. 13F-HR data is a 45-day-lagged snapshot — see 45-day lag explained and methodology.