Jonathan A. Karen

Partner

425 Lexington Avenue

New York, NY 10017

Email: jkaren@stblaw.com

Phone: +1-212-455-3274

Fax: +1-212-455-2502

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Jonathan Karen is a partner in the Firm’s Corporate Department, where he is Co-Head of the Investment Funds Practice, Co-Administrative Partner of the Firm and member of the Firm's Executive Committee, the Firm's highest governing body. Jonathan has led the Firm’s recent efforts in some of the industry’s most successful and market-defining private equity fund formations across innovative sectors such as artificial intelligence and digital infrastructure, as well as traditional strategies including buyout, real estate, credit and secondaries, with notable representations such as BlackRock / GIP, Microsoft and MGX's Global AI Infrastructure Investment Partnership ($30 billion, 2025), Arlington Capital Partners VII ($6 billion, 2025) and Stonepeak's recent flagship and related infrastructure funds: Stonepeak Infrastructure Fund IV ($14 billion, 2020), Stonepeak Opportunities Fund ($3.15 billion, 2024) and Stonepeak Asia Infrastructure Fund ($3.3 billion, 2024), along with their respective successor funds. His recent work also encompasses Blackstone's recent flagship corporate, energy and real estate private equity funds: Blackstone Capital Partners Asia III ($13.1 billion, 2026), Blackstone Capital Partners IX ($21 billion, 2025), Blackstone Real Estate Partners X ($30.4 billion, 2023) and Blackstone Core Equity Partners II ($8 billion, 2020). Other noteworthy clients include Apollo, Carlyle, MGX, Haveli Investments, Centerbridge, HGGC, Rockpoint, Manulife, Calera Capital, Madison International Realty and other leading firms. Jonathan has also advised on numerous other separate accounts, funds-of-one and similar custom arrangements across multiple asset classes, including buyout, real estate, infrastructure, secondaries and distressed and mezzanine debt. Jonathan also counsels investment firms on a mix of matters involving private investment funds, including firm capitalization and liquidity, succession planning, internal economic arrangements, regulatory compliance, M&A transactions and strategic investments involving private fund sponsors, joint ventures and spin-outs. Jonathan is ranked Band 1 for fund formation by both Chambers USA and Chambers Global, which quote clients describing him as “an ideal partner for nuanced work” with “impeccable commercial awareness” (Chambers USA) and “phenomenal” (Chambers Global). He is also recognized as a Leading Partner for fund formation by The Legal 500. Jonathan was recognized as Fund Formation “MVP” by Law360 in 2023 and 2021, named to Private Equity International’s (PEI) Private Funds Management’s “30 Rising Stars Under 40” in 2015 and labeled a “Rising Star” by Law360 in 2013.

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Work Highlights

BlackRock / Global Infrastructure Partners (GIP), Microsoft and MGX in the establishment of the $30 billion Global AI Infrastructure Investment Partnership
Arlington Capital Partners in the establishment of the $6 billion Arlington Capital Partners VII
Blackstone in multiple fundraisings, including the establishment of the $30.4 billion Blackstone Real Estate Partners X, the largest real estate or private equity drawdown fund ever raised, the $21 billion Blackstone Capital Partners IX, the $13.1 billion Blackstone Capital Partners Asia III, the $20.5 billion Blackstone Real Estate Partners IX, the $8 billion Blackstone Core Equity Partners II, the $6.4 billion Blackstone Capital Partners Asia II, and the $4.2 billion Blackstone Energy Partners III
Stonepeak Infrastructure Partners in the establishment of the $14 billion Stonepeak Infrastructure Fund IV, the $7.2 billion Stonepeak Infrastructure Fund III, the $3.3 billion Stonepeak Asia Infrastructure Fund, the $3.15 billion Stonepeak Opportunities Fund, and the $2.75 billion Stonepeak Global Renewables Fund, its inaugural renewable energy fund
Centerbridge Partners in the establishment of the approximately $3 billion Centerbridge Capital Partners IV and prior funds
Rockpoint in the establishment of the $5.4 billion Rockpoint Real Estate Fund VII, the $3.8 billion Rockpoint Real Estate Fund VI, and the $2 billion Rockpoint Growth and Income Real Estate Fund III

Accolades

2023 “MVP” in Fund Formation, Law360
2021 “MVP” in Fund Formation, Law360

Education

New York University School of Law, 2001 J.D.
Annual Survey of American Law, 1999–2000
Duke University, 1998 B.A.
cum laude

Admissions

New York 2002

Jonathan A. Karen, a Partner at Simpson Thacher & Bartlett LLP practicing in the Firm’s Corporate Department, Co-Head of the Investment Funds Practice, Co-Administrative Partner of the Firm and a member of the Firm's Executive Committee, has led the Firm’s recent efforts in some of the industry’s most successful and noteworthy private equity fund formations across innovative sectors such as artificial intelligence and digital infrastructure, as well as traditional strategies including buyout, real estate, credit and secondaries, including:

BlackRock / GIP, Microsoft and MGX’s $30 billion Global AI Infrastructure Investment Partnership (2025)
Arlington Capital Partners VII – $6 billion (2025)
Stonepeak’s recent flagship and related infrastructure funds:
- Stonepeak Infrastructure Fund IV ($14 billion; 2020) and successor fund
- Stonepeak Opportunities Fund ($3.15 billion; 2024) and successor fund
- Stonepeak Asia Infrastructure Fund ($3.3 billion; 2024) and successor fund
Blackstone’s recent flagship corporate, energy and real estate private equity funds:
- Blackstone Capital Partners Asia III – $13.1 billion (2026)
- Blackstone Capital Partners IX – $21 billion (2025)
- Blackstone Real Estate Partners X – $30.4 billion (2023)
- Blackstone Core Equity Partners II – $8 billion (2020)

Other noteworthy clients include Apollo, Carlyle, MGX, Haveli Investments, Centerbridge, HGGC, Rockpoint, Manulife, Calera Capital, Madison International Realty and other leading firms.

Jonathan is ranked Band 1 for fund formation by both Chambers USA and Chambers Global, which quote clients describing him as “an ideal partner for nuanced work” with “impeccable commercial awareness” (Chambers USA) and “phenomenal” (Chambers Global). He is also recognized as a Leading Partner for fund formation by The Legal 500. Jonathan was named to Private Equity International's (PEI) Private Funds Management’s “30 Rising Stars Under 40” recognizing the top private funds lawyers under 40 as identified by industry participants and law firms from around the world. He was featured in Law360 as 2023 and 2021 “MVP” in Fund Formation and 2013 "Rising Star,” all of which honored his work for several high-profile private equity clients in establishing multibillion-dollar fund formations. Jonathan was also cited as a recommended private equity funds lawyer in Who’s Who Legal 2015. Jonathan has also spoken about private funds at forums such as the International Bar Association’s Private Funds Conference in London as well as the New York City Bar Association. His published work includes articles in Private Equity International and Getting the Deal Through.

Jonathan also counsels investment firms on a mix of matters involving private investment funds, including firm capitalization and liquidity, succession planning, internal economic arrangements, regulatory compliance, M&A transactions and strategic investments involving private fund sponsors, joint ventures and spin-outs.

Jonathan received his J.D. from New York University School of Law in 2001, where he edited the Annual Survey of American Law from 1999 to 2000. He received his B.A. from Duke University, cum laude, in 1998.