Adam S. Aderton - Partner

A former senior official in the SEC’s Enforcement Division, Adam Aderton focuses on regulatory and enforcement matters, with a particular emphasis on advising clients across the asset management industry. He has deep experience in complex regulatory inquiries and litigation matters involving private equity funds, venture capital funds, hedge funds, BDCs, mutual funds and ETFs, as well as separately managed accounts. He also provides asset managers with practical ongoing compliance advice. Adam is a thought leader in the space, regularly speaking on asset management enforcement issues to leading industry groups, including the Investment Adviser Association, the Investment Company Institute and the Institutional Investor Legal Forum, among others.

Amanda K. Allexon - Partner

Amanda K. Allexon combines nearly a decade of service at the Federal Reserve Board and robust private practice experience to provide domestic and foreign financial institutions and investors with sophisticated, commercial advice on the full spectrum of transactional, governance, regulatory and supervisory matters, including complex high-profile mergers and acquisitions. She routinely represents clients before the Federal Reserve, the Office of the Comptroller of the Currency, the Federal Deposit Insurance Corporation and U.S. state banking regulators. She also advises on private equity investments involving banks and bank holding companies, and Volcker Rule issues.

David W. Blass - Partner

Co-Managing Partner of the Firm’s Boston office, David Blass is a leading regulatory lawyer in the funds industry and has advised on matters involving innovative registered funds products, Investment Advisers Act compliance, SEC examination and enforcement matters, and broker-dealer regulatory compliance. He is uniquely qualified to provide strategic and regulatory advice on matters involving asset management firms and broker-dealers. 

David has extensive knowledge of the regulatory requirements of the asset management industry having  served as General Counsel of the Investment Company Institute, the trade association for registered investment funds.  He also held senior roles for over a decade at the U.S. Securities and Exchange Commission, most recently as Chief Counsel and Associate Director in the Division of Trading and Markets, where he oversaw broker-dealer regulation and large aspects of FINRA’s regulatory program.  David was the Associate General Counsel for the SEC where he was responsible for Dodd-Frank Act implementation, among many other programmatic areas.  He also held a senior role in the SEC’s Division of Investment Management, leading the office regulating registered investment advisers, including advisers to private funds.

Chambers Global reports that clients say he is an “excellent regulatory lawyer” who is both “very knowledgeable and easy to work with.” David was notably named “Independent Counsel of the Year” by Fund Intelligence’s Mutual Fund Industry & ETF Awards in 2021.

Benjamin A. Bodurian - Partner

Benjamin Bodurian regularly advises private equity firms and public and private companies in connection with mergers and acquisitions, investments, dispositions, joint ventures and other corporate transactions. He has experience representing clients across a variety of sectors including healthcare, technology, financial services and industrials and manufacturing. Benjamin’s clients have included private equity firms such as BC Partners, Carlyle and EQT as well as large corporations such as AGCO, Change Healthcare, Garda World Security Corporation and TD Bank.

Lindsey C. Bohl - Partner

Lindsey Bohl focuses her practice on matters involving all aspects of antitrust and competition law. This includes merger reviews and counseling clients considering M&A transactions across a wide range of industries, including healthcare, retail, consumer products, technology and medical devices and pharmaceutical products, as well as government antitrust investigations and antitrust litigation. Lindsey was previously a staff attorney in the FTC’s Mergers IV Division, where she led significant healthcare and retail transaction investigations and litigated merger challenges.

Joshua Ford Bonnie - Partner Co-Head of the Firm’s Global Capital Markets Practice, Co-Managing Partner of the Firm’s Boston and Washington, D.C. offices, and a member of the Executive Committee, Josh Bonnie is one of the nation's preeminent IPO lawyers and regularly counsels public companies on significant strategic transactions, capital markets offerings and general corporate and securities law matters. Josh’s transactional experience also includes business combinations involving special purpose acquisition companies. Josh has been featured in The American Lawyer’s “Dealmakers of the Year,” is recognized in Chambers Global: The World’s Leading Lawyers for Business, Chambers USA: America’s Leading Lawyers for Business and is endorsed by PLC Which Lawyer?. Josh was recently added to The Legal 500’s “Hall of Fame” for Capital Markets: Equity Offerings in recognition of his role as one of the leading capital markets practitioners in the United States.

Nathan Briggs - Partner

A Partner in Simpson Thacher’s Registered Funds Practice, Nathan Briggs advises registered investment vehicles, investment advisers and independent directors across the full spectrum of formation, transactional, governance and compliance issues. These range from new product offerings and follow-on offerings, proxy contests and fund mergers and consolidations to ongoing compliance and governance matters. He advises sponsors with respect to, among other products, listed closed-end funds, interval funds, tender offer funds, REITs and business development companies in connection with the establishment, registration, reorganization and operation of retail and institutional investment products.

Ryan Brizek - Partner

A Partner in the Firm’s Registered Funds Practice, Ryan Brizek focuses his practice on transactional and regulatory matters involving regulated funds, with a particular focus on making private markets investment strategies accessible to public investors. Ryan advises clients on the formation and operation of investment funds and other products designed to provide retail and high net worth investors access to alternative asset classes, such as private equity, private credit, infrastructure, secondaries and liquid alternatives. He has deep experience across the various types of regulated fund structures, including interval funds, tender offer funds, listed closed-end funds, business development companies, mutual funds and exchange-traded funds.

Chambers USA recognizes Ryan in the area of Registered Funds and IFLR 1000 recognizes Ryan as “Highly Regarded” in the area of Registered Funds. The Legal 500 commends Ryan for his experience as fund counsel to registered funds implementing private markets strategies sponsored by some of the largest asset managers.

Justin L. Browder - Partner

Justin Browder is a Partner in the Firm’s Registered Funds and Funds Regulatory and Investigations Practices. He counsels investment advisers, private and registered investment funds and broker-dealers on all aspects of the federal securities laws, with a particular emphasis on the Investment Advisers Act of 1940 and the Investment Company Act of 1940. Justin has substantial experience advising private fund managers and sponsors of wealth management and separately managed account programs concerning a wide variety of operational, transactional and adversarial matters. A central component of his practice involves representing advisers, funds and wealth management firms in SEC examinations and enforcement proceedings. Justin is also a recognized practitioner in the area of digital assets, where he advises asset managers and exchange platforms on compliance and operational matters. Additionally, Justin’s experience includes representing financial sponsors and strategic investors concerning mergers, acquisitions and spin-outs of asset management businesses and advising alternative asset managers on fund formation matters. Earlier in his career, Justin served as Assistant General Counsel at a large alternative asset management firm in New York where he advised on a range of regulatory and transactional matters.

Justin has been recognized as a leading lawyer in the Investment Funds: Regulatory & Compliance category by Chambers USA (2021-2024), Chambers Global (USA) (2022-2025), and Chambers FinTech Legal: Blockchain & Cryptocurrencies (2024). He is also a recommended lawyer in Finance: Fintech by Legal 500 US (2022-2023).

Christopher Brown - Partner

Chris Brown concentrates his practice on banking and finance. He has represented private equity sponsors and their portfolio companies, as well as public and private companies, in a wide variety of secured lending and other financing transactions. In addition, Chris has worked for many clients on matters involving general secured finance issues, debt restructurings and related corporate issues. His clients have included AEA Investors, Alterra Mountain Company, AMG, Angeles Equity Partners, Best Buy, BlackRock, Blackstone, Cimpress, Evercore Partners, Cohen & Steers, Frontdoor, Hershey, Ingersoll Rand, JLL Partners, KKR, KSL Capital Partners, Microsoft, New Mountain Capital, Primavera Capital Partners, Riverstone, Stonepeak Infrastructure Partners, Twitter and ZoomInfo.

Vanessa K. Burrows - Partner

Based in the Firm’s Washington, D.C. office, Vanessa represents clients in healthcare regulatory matters, including those involving the Food and Drug Administration (FDA). Vanessa has advised pharmaceutical and medical device manufacturers, healthcare and technology companies, hospitals and other providers in connection with regulatory and compliance needs, as well as in connection with M&A and capital-raising transactions. Vanessa has extensive experience counseling clients with respect to FDA regulatory and enforcement matters, health privacy, security and breach issues, healthcare fraud and abuse matters and cannabis and hemp laws.

Rajib Chanda - Partner

Hailed as a “Trailblazer” by the American Lawyer for his legal contributions to the democratization of access by ordinary investors to private markets investments, Rajib heads Simpson Thacher’s Registered Funds practice and is Co-Managing Partner of the Washington, D.C. office. Rajib has helped asset management firms design, develop and structure investment products that have been publicly referred to as “revolutionary,” “category-killing” and “the fund innovation of the year.” Rajib regularly represents the leading asset management firms in the world, including recent representations of Apollo, Artisan Partners, BC Partners, Benefit Street, BlackRock, Blackstone, Blue Owl, Carlyle, Cohen & Steers, Coller Capital, Diameter Capital, EQT, Golub, HarbourVest, HPS, Irradiant Partners, JPMorgan Asset Management, KKR, Lexington Partners, Morgan Stanley, New Mountain, Onex Credit, Principal, Sixth Street Partners, SkyBridge Capital, Starwood Capital Group, Stonepeak, TPG, TPG Angelo Gordon and Vista, among many others.

Anne C. Choe - Partner

Anne C. Choe is a Partner in the Firm’s Registered Funds and Funds Regulatory and Investigations Practices and represents investment managers, registered funds and private funds on a broad range of regulatory and transactional matters. Her experience covers a variety of fund structures, including exchange-traded funds, mutual funds and private funds. Anne also regularly counsels family offices and independent boards and has in-depth knowledge of the various securities and other laws applicable to investment managers and funds, including the Investment Company Act of 1940 and the Investment Advisers Act of 1940. She additionally represents investment advisers and funds in SEC examination and enforcement matters. Anne has significant experience advising investment management firms in registering with the SEC as investment advisers, as well as advising on exemptions from registration for U.S. and non-U.S. firms.

Brian D. Christiansen - Partner

With more than two decades of experience, Brian Christiansen is recognized as one the country’s foremost financial services lawyers. He counsels U.S. and international banking organizations, nonbank financial services firms and their investors and counterparties on all types of regulatory, transactional, compliance and enforcement matters. Brian is lauded by Chambers USA as “a highly skilled transactional and regulatory attorney, who offers specialized counsel to financial services firms,” with clients noting that he “is a very strong and pragmatic bank regulatory lawyer.”

Toby Chun - Partner

As Co-Head of the Environmental Practice, Toby Chun focuses on the environmental aspects of complex, and often cross-border, transactions. Recognized by Chambers USA, The Legal 500 and others, he has developed deep experience in advising a diverse range of businesses across numerous industries in the United States and around the world. 

Jonathan L. Corsico - Partner

Jonathan Corsico leads the Firm’s Mergers and Acquisitions practice in Washington, D.C. He specializes in transactions that are unusually complicated or difficult, such as those facing significant antitrust risk or those utilizing novel terms. Within his broader practice, Jon has become one of the preeminent lawyers in the country in the growing field of M&A involving registered investment funds. 

In addition to M&A, Jon also counsels clients on forming new businesses, joint ventures, fund adoptions, stockholder activism defense, corporate governance and minority investments.

Jon’s prior representations span multiple industries, from asset management, to healthcare, to gold mining.

Some of Jon’s recent clients include Ally Financial, Apollo, BC Partners, Benefit Street, Carlyle, Castlelake, Change Healthcare, Cross Country Healthcare, Diameter Capital Partners, EJF Capital, Franklin Templeton, Herc Rentals, Hilton Grand Vacations, Hilton Hotels & Resorts, Mattress Firm, Meridian Capital, McKinsey & Company, NewPoint Real Estate Capital, Republic Airways, Sands Capital, SkyBridge Capital, Supernova Partners, TPG Angelo Gordon and USAA.

Jon has been listed in Chambers and Partners since 2018, and is described by clients as “an outstanding attorney”. In 2016, Jon was named an M&A “Rising Star” by Law360. Outside of the law, Jon is the inventor of two patents in the field of professional level motorsports.

Elizabeth J. DiSciullo - Partner

Beth DiSciullo regularly advises public and private companies and private equity sponsors on mergers and acquisitions, strategic investments, dispositions, joint ventures and other corporate transactions across a wide range of industries. Beth’s clients have included Microsoft, Blackstone, Charlesbank, The Mosaic Company, The Bountiful Company and Apax Partners, among others.

Katherine S. Draper - Partner Katherine Draper is a Partner in the Firm’s Corporate Department and Securitization Practice. Kate’s practice encompasses securitizations involving many different types of asset classes, including digital infrastructure (such as data centers, cell towers and fiber networks), auto loans and leases, fleet leases, rental cars, whole-business securitizations and other esoteric assets. Kate represents both issuers and underwriters, as well as parties in acquisitions and other transactions in which securitizations are involved.

Abram J. Ellis - Partner

Recognized as a “Rising Star” and “Next Generation Partner” in antitrust litigation and cartels, Abram Ellis is a Partner in the Firm’s Washington, D.C. office. His practice comprises all aspects of competition law, from defending clients against complex class action antitrust litigation to helping clients obtain regulatory clearance from domestic and international competition authorities for significant transactions. Abram is particularly experienced in antitrust litigation involving complex financial instruments, the healthcare industry and employment issues. He has been recognized for his antitrust work in Euromoney’s Benchmark Litigation and The Legal 500, where he is described as “highly regarded in the market,” “a leader in the field,” and “a good strategist.” Sources also say that he is “a phenomenal advisor—both on day to day advisory matters, but also on complex litigation . . . He is a star.”

In addition to his robust antitrust practice, Abram advises clients on a range of regulatory matters. As Co-Head of the Firm’s International Trade Regulation Practice, he advises leading private equity funds, financial institutions and major corporations on regulatory and compliance matters relating to cross-border activities, including with respect to anti-money laundering (including CTA compliance), OFAC, FCPA and export matters. Abram also advises on anti-money laundering issues, including compliance with the Corporate Transparency Act and FinCEN’s Beneficial Ownership Information rule. 

Crystal L. Frierson - Partner

Crystal Frierson is a Partner in the Firm’s Private Funds Practice. She advises sponsors on the formation, structuring and management of private investment funds across a range of asset classes as well as on co-investments and separately managed accounts. She also counsels clients in respect to private investments in alternative asset managers. Crystal regularly represents some of the largest and most prominent fund sponsors including The Carlyle Group, Blackstone, Hellman & Friedman and Platinum Equity.

William R. Golden - Partner

Based in Washington, D.C., Will Golden is a Partner in the Firm’s Capital Markets Practice. Will represents issuers, private equity sponsors and underwriters in a wide range of securities offerings, including initial public offerings, follow-on and secondary equity offerings, spin-offs, high yield and investment grade debt offerings and acquisition financing transactions, as well as exchange offers and other liability management transactions. Will also advises clients on ongoing public reporting, compliance and corporate governance matters.

David J. Greene - Partner Based in our Washington, D.C. office, David J. Greene is a Partner in the Firm’s Investment Funds Practice. David’s practice focuses on private fund formation and operation, as well as related alternative assets. He has represented sponsors in their global fundraising activities including energy and infrastructure funds, natural resource funds and other private investment vehicles. David regularly publishes articles on topics relating to the private funds industry and has been recommended by The Legal 500 United States. Named a “DC Rising Star” by The National Law Journal, David was also recently recognized at Euromoney’s “Americas Rising Stars” awards for his work forming the $18.5 billion Carlyle Partners VII fund.

David has represented a number of preeminent private fund sponsors in various fundraisings, including Morgan Stanley, The Carlyle Group, New Mountain, KKR, Integrum and SoftBank Group. Prior to joining Simpson Thacher, David also advised Denham Capital, LLR Partners, Penfund and Juniper Capital.

Steven Grigoriou - Partner

Steven Grigoriou is a Partner in the Firm’s Registered Funds Practice, where he advises a wide array of registered funds, business development companies and multinational investment advisers on a broad range of corporate transactions. He regularly represents public funds, fund sponsors, investment advisers, investment banks and other financial institutions on the design, formation and structure of investment funds and products, securities offerings, regulatory and compliance matters, as well as other corporate matters. Steven was named a “Rising Star” at the 2021 Fund Intelligence Mutual Funds Industry & ETF Awards. 

James W. Hahn - Partner

Jamie Hahn advises investment funds and other vehicles on a broad range of formation, transactional and regulatory matters, with a particular focus on making private market strategies accessible to public investors. He advises clients on the initial design, formation and ongoing operation of regulated funds and other vehicles seeking to provide sophisticated retail and high-net-worth individuals exposure to alternative asset classes, including asset-backed credit, infrastructure, private equity and real estate. While Jamie primarily focuses his practice on innovative structures for conglomerate and holding companies, private funds and private REITs, he also has experience working with registered funds, including mutual funds, closed-end funds and ETFs.  

Anat Holtzman - Partner

Anat Holtzman has deep experience in the formation, fundraising and operation of private investment funds across a multitude of strategies, including buyout, credit, real estate and energy and infrastructure funds. She also advises fund sponsors on the development of private fund products that focus on the private wealth channel, among others. Previously a Managing Director at Carlyle in the Legal and Compliance Department, she served as Head of Fund Formation for the Global Private Equity segment.

Daniel B. Honeycutt - Partner

Daniel Honeycutt is a Partner in the Firm’s Registered Funds Practice. Based in the Firm’s Washington, D.C. office, he provides creative and sophisticated counsel to a diverse array of companies in the financial services and real estate industries, with extensive experience advising REITs on a wide range of formation and transactional matters. Daniel guides clients through complex public and private capital raising matters, including initial public and private offerings and follow-on offerings, as well as significant preferred stock and debt offerings.

Sage E. Hughes - Partner

Sage Hughes is a Partner in the Firm’s Private Funds Practice and regularly advises some of the largest and most well-established private investment fund sponsors, including Blackstone, The Carlyle Group, HarbourVest, KKR and Morgan Stanley. She focuses on the formation, structuring and operation of onshore and offshore private investment funds and has deep experience in assisting sponsors on the development of vehicles across a range of strategies, including buyout, growth, infrastructure, credit, real estate and many others. Sage also regularly advises sponsors on governance and other internal sponsor arrangements, “funds-of-one,” separately managed accounts, co-investment vehicles, structured secondary transactions and regulatory compliance matters, as well as in connection with their investments in other asset managers.

Karen Kazmerzak - Partner

A former Federal Trade Commission (FTC) lawyer, Karen Kazmerzak advises clients on a wide range of antitrust and competition issues, particularly in seeking clearance for high-profile, complex mergers and acquisitions before the Department of Justice and FTC, and in developing strategies to advocate for merger approval in international jurisdictions. Recognized as a leader in the field by Chambers USA, Legal 500 and a “Litigation Star” by Euromoney’s  Benchmark Litigation, she is lauded by clients as “deeply knowledgeable, extremely practical and commercially minded.” Karen is also recognized for her work representing third-party market participants in connection with opposition to acquisitions and in connection with government subpoenas.

Karen’s extensive private sector and government experience has spanned numerous industries, including the life sciences, energy, transportation, healthcare and telecom sectors, among many others. She also counsels clients on antitrust matters involving licensing, distribution, pricing and competitor collaborations.

Meaghan A. Kelly - Partner

Meaghan Kelly is a Partner in the Firm’s Investment Funds Practice and a key member of the Firm’s Funds Regulatory and Investigations Practice. Meaghan specializes in counseling various types of fund sponsors across a host of regulatory and enforcement matters. In particular, Meaghan is integral to the Firm’s SEC examination practice—counseling clients on examination preparation, guiding clients through examinations, and advising on creative and achievable solutions post-examination. In addition, Meaghan represents investment advisers in high-stakes SEC enforcement investigations. Meaghan is regarded as a uniquely skilled and experienced regulatory and enforcement defense lawyer, having a pulse on SEC expectations and market practice. She also routinely counsels on questions with respect to the Investment Advisers Act, and provides practical and informed solutions to compliance and disclosure questions. Her clients include sponsors to private equity funds, hedge funds, venture capital funds, credit funds, infra funds, real estate funds, as well as registered funds. Meaghan routinely leads internal investigations involving myriad complex and sensitive issues for investment advisers, and also has developed in-depth understanding of more recent and emerging areas, such as regulatory and compliance matters related to cryptocurrency and other digital assets, and artificial intelligence (AI). Meaghan also has experience representing financial institutions in connection with Congressional investigations and related Congressional hearing preparation. Meaghan is a frequent presenter, author, and commentator on SEC regulatory and compliance developments for the asset management industry.

Meaghan also maintains a broad robust investigations and SEC enforcement defense practice for financial institutions, public companies, and individuals, both in the United States and abroad. In 2023, she received the Burton Award for Distinguished Legal Writing in connection with her article titled “The Importance of the ‘How’ and the ‘Why’ in SEC Settlements.” Additionally, Meaghan was named to Global Investigation Review’s 2020 “40 Under 40,” which profiles 40 leading young investigations specialists from around the world. 

Jeffrey H. Knox - Partner

Jeff Knox, former head of the U.S. DOJ Fraud Section, is Co-Managing Partner of Simpson Thacher’s Washington, D.C. office and Global Co-Head of the Firm’s Government and Internal Investigations Practice. He represents multinational corporations and independent board committees in high-stakes investigations by the DOJ, SEC, CFTC, CFPB, and other federal and state enforcement regulators. He has advised some of the world’s leading financial institutions, energy companies, life sciences companies, and technology firms in navigating criminal and civil investigations relating to the FCPA, securities and accounting fraud, market manipulation, False Claims Act, antitrust, international money laundering, economic sanctions, and environmental crimes. Jeff also represents senior executives, in their individual capacity, who are subjects of enforcement investigations. Jeff has served as a government-appointed independent compliance consultant, and represents companies in government and court-mandated monitorships. Prior to joining the Firm, Jeff served as a federal prosecutor for more than a decade, including as the Chief of the DOJ’s Fraud Section in Washington, D.C., and before then, as the Chief of the National Security Section of the U.S. Attorney’s Office for the Eastern District of New York. 

Jeff is recognized as a Band 1 FCPA lawyer by Chambers USA and Chambers Global, and as a “Leading Lawyer” by The Legal 500. Jeff has been named a White Collar MVP by Law360, and is consistently recognized by Chambers USA, Chambers Global, The Legal 500 and Euromoney’s Benchmark Litigation, where sources note him as “one of the best lawyers in the country,” “spectacular, hardworking,” “brilliant with an incredible depth of knowledge,” and “a master strategist with a unique insight into the way the DOJ works,” who “understands cases from multiple different dimensions,” and has “a good combination of substantive expertise and practical knowledge” that “really adds value to the client.” In 2024, Jeff was named a “Distinguished Advisor” in Financier Worldwide’s list of ten “Power Players” worldwide in Investigations & White-Collar Crime. He is a respected voice on corporate compliance and enforcement policy, and serves on advisory boards dedicated to these issues at NYU School of Law and the American Law Institute.     

Preston Miller - Partner

Preston Miller focuses on antitrust and competition law. With a particular emphasis on merger review, he has extensive experience obtaining regulatory clearances from domestic and international competition authorities for high-profile, often cross-border, transactions across a wide variety of industries. Preston has been recognized by both Chambers USA and The Legal 500 U.S. for his antitrust counseling on complex corporate transactions. He is described in The Legal 500 as “such a strong lawyer that partners from other firms routinely acknowledge the benefits of having him on the other side as someone who will be efficient, practical, friendly and able to lead a very strong case.” Preston also has experience in defending clients in complex class action antitrust litigation and government antitrust investigations. In 2024, Preston was recognized on Euromoney’s  Benchmark Litigation’s “40 & Under List,” which honors the top emerging talent in litigation. He was also recognized as a “DC Rising Star” by The National Law Journal in 2023.

Benjamin S. Persina - Partner

Benjamin Persina is a Partner in Simpson Thacher’s Washington, D.C. office and a member of the Firm’s Banking and Credit Practice. He represents private equity sponsors and their portfolio companies, as well as public and private companies, in a wide variety of secured lending, direct lending, and other financing transactions. He also regularly represents leading financial institutions and investment banks with the arrangement and syndication of senior credit facilities, including acquisition, bridge and other corporate financings. His clients have included, among many others, Blackstone, Cimpress, First Eagle Alternative Capital BDC, Hellman & Friedman, JPMorgan, New Mountain Capital, Silver Lake, Stonepeak and Twitter.

Karen Porter - Partner

Karen Porter is a Partner in the Firm’s Litigation Department, practicing in the Washington, D.C. office. Karen focuses on cross-border government and internal investigations as well as antitrust, corporate governance and compliance matters. She also represents clients in a wide range of high-profile, complex commercial litigation matters, including securities, class action and shareholder derivative litigations. Karen has experience managing sensitive, high-stakes regulatory and criminal matters—including interactions with senior management, board committees, external auditors and government regulators—as well as follow-on litigation. Karen also has experience advising senior officers and directors in global antitrust, money laundering and sanctions investigations. In 2023 and 2024, Karen was recognized on Euromoney’s  Benchmark Litigation’s “40 & Under List,” which honors the top emerging talent in litigation. Karen is a Fellow of the American Bar Foundation and a member of The American Law Institute.

Sara Y. Razi - Partner

Sara Razi is Global Co-Chair of the Firm’s Antitrust and Trade Regulation Practice. She is a leading antitrust attorney, focusing on merger reviews, government antitrust investigations, antitrust litigation, and counseling on a variety of competition issues. Sara joined Simpson Thacher in 2013 from the FTC, where she served in senior roles for nearly a decade.

Sara regularly represents clients in antitrust investigations by the DOJ, FTC, and States and has secured successful outcomes in several complex and closely-watched mergers and high-profile antitrust litigations. Her extensive private-sector and government antitrust experience spans a multitude of industries including healthcare, pharmaceuticals, technology, supermarkets and other retailers, consumer products, financial services, media, and telecommunications.

Sara is recognized by The Legal 500 as a “Leading Lawyer” and by Chambers USA. Sources note that she is “a very seasoned and knowledgeable antitrust attorney” who “has the unique ability to give very practical advice about how regulators would react to matters,” with “extensive knowledge of agency strategy.” Sara is also ranked as one of the “Top 250 Women in Litigation” in the U.S. by Euromoney’s Benchmark Litigation, where she is highlighted for her “antitrust acumen” and “trial prowess” displayed during a recent merger litigation. In 2024, Sara was named “Antitrust Litigator of the Year” by Euromoney’s Benchmark Litigation, and in 2023, she was named a “MVP” in Competition/Antitrust by Law360; a Litigation “Trailblazer” by The National Law Journal; “Antitrust & Competition Lawyer of the Year” by Euromoney’s Women in Business Law Americas Awards; and among The Deal’s “Top Women in Dealmaking.” In 2025 she was again featured as one of Global Competition Review’s “Women in Antitrust” where she is separately described by GCR as one of the “best FTC merger advisers in the business.” Sara is an authority on antitrust issues and speaks frequently at conferences sponsored by the ABA, law schools, and private organizations. She also serves as Co-Chair of the Firm’s Pro Bono Committee and as a member of the DC Legal Aid board of trustees. 

Nicholas Olumoya Ridley - Partner

Nicholas Ridley is a Partner in the Firm’s Investment Funds Practice. Based in the Firm’s Washington, D.C. office, Nicholas focuses on complex regulatory and transactional matters including providing sponsor and adviser clients with practical and creative solutions to regulatory, compliance and enforcement issues. Named a 2024 “Rising Star” in the investment funds space by With Intelligence, Nicholas has extensive experience collaborating with clients to develop innovative retail products, pursue novel applications for SEC exemptive relief and address emerging compliance and regulatory considerations impacting asset managers, private funds, registered funds, business development companies (BDCs) and fund boards. In addition, Nicholas frequently counsels both asset management and operating company clients on complicated “status” issues under the Investment Company Act. He has represented preeminent sponsors and investment managers such as AMG, Apollo, BC Partners, Blackstone, Carlyle, JPMorgan Asset Management, KKR, PIMCO and SkyBridge Capital, among others.

Benjamin Rippeon - Partner

A Partner in the Firm’s Tax Practice, Benjamin Rippeon provides a wide range of clients with sophisticated, solutions-oriented advice related to domestic and international tax issues. He focuses on tax planning for investment funds and strategic corporate and real estate acquisitions, dispositions and reorganizations. His diverse group of clients include corporations, investment funds, joint ventures, partnerships, limited liability companies and special purpose acquisition companies (SPACs). Benjamin has also advised on the formation of numerous private REITs in connection with real estate acquisitions and dispositions involving U.S. and non-U.S. investors, including sovereign wealth funds.

Adam Z. Risell - Partner

Adam Risell advises asset managers and sponsors in connection with a broad range of capital raising activities utilizing structured finance technology, including the formation of complex investment vehicles, such as rated note fund structures, collateralized fund obligations (“CFOs”), and securitizations and other capital-efficient investment products, including those designed for investment by insurance companies. He also advises on the development and distribution of collateralized loan obligation (“CLO”) captive funds, risk retention vehicles and other similarly specialized funds. Adam also counsels business development companies (“BDCs”) and other registered funds relating to structured financing techniques.

Carleigh Rodriguez - Partner

As Co-Head of the Firm’s Environmental Practice, Carleigh Rodriguez advises private equity and corporate clients on environmental issues arising in the full array of commercial transactions, including mergers, acquisitions, divestitures, securities and financing transactions, bankruptcies and restructurings, across a broad range of U.S. and international industries. Her work also includes pre-deal counseling and post-closing resolution of environmental issues. Recognized by The Legal 500 U.S. as a leading lawyer in Environment: Transactional, Carleigh provides practical and commercial advice for managing environmental liabilities and risks.    

Erica Rozow - Partner

Erica focuses on ERISA fiduciary matters and works closely with the Firm’s investment fund clients on issues related to the formation and fundraising of funds, including plan asset rules and venture capital operating company and real estate operating company structuring, and other exemptions. She works closely with fund clients across numerous strategies, including private equity, real estate, infrastructure, growth, credit and debt, and many others. Her practice also includes ERISA matters in the funds’ related mergers and acquisitions and investment work.

Mark B. Skerry - Partner

Mark Skerry advises some of the world’s largest and most well-known private equity asset managers, institutional investors, and multinational corporations on transactions undergoing national security reviews before the Committee on Foreign Investment in the United States (CFIUS) and analogous foreign direct investment (FDI) screening regulators worldwide. Mark has successfully secured CFIUS approvals and coordinated worldwide FDI clearances for transactions across a variety of industries considered sensitive to national security, including aerospace and defense manufacturing, classified government contracting, sea and airports, semiconductors, telecommunications, technology and software, social media, energy infrastructure, financial services, and life sciences, among others. Mark has been recognized by Chambers USA, The Legal 500, Law360, IFLR1000, and Benchmark Litigation for his achievements on numerous high-profile and cross-border transactions.

Spencer A. Sloan - Partner

A Partner in Simpson Thacher’s Financial Institutions Practice, Spencer Sloan’s practice focuses on advising domestic and international financial institutions, their affiliates and counterparties in connection with regulatory, supervisory, enforcement and transactional matters. Spencer regularly counsels U.S. and foreign banks, other regulated financial services firms and their investors in connection with mergers and acquisitions, strategic investments, and capital markets transactions. He also advises banking clients on regulatory compliance matters, new activities and charters, and routinely practices before the major financial services regulators, including the Federal Reserve Board, the Office of the Comptroller of the Currency and the Federal Deposit Insurance Corporation, as well as state banking regulators. Spencer was recently recognized as a Law360 “Rising Star” in the banking sector.

Neesa Patel Sood - Partner

As a Partner in the Registered Funds Practice, Neesa Patel Sood advises registered funds, their investment advisers and independent board members across a wide range of complex regulatory, compliance, fund governance, operational and transaction-related matters. She regularly provides advice regarding the structuring, launch and day-to-day operations of registered funds. Neesa also has significant transactional experience, counseling clients on fund restructurings as well as fund and adviser merger and acquisition transactions.

Neesa is recognized by The Legal 500 U.S. (2023-2024) as a “Next Generation Partner” for Investment Fund Formation and Management: Mutual/Registered/Exchange-Traded Funds and for her work in Registered Funds by Chambers Global (2023-2025) and Chambers USA (Nationwide) (2022-2024). In addition, With Intelligence named Neesa as Independent Counsel of the Year at its 2023 Mutual Fund and ETF Awards. She was also named a “Rising Star” at Fund Intelligence’s 2021 Mutual Fund and ETF Awards.

Audrey Stern - Partner

M. Kathryn Stone - Partner

Kathryn Stone advises asset managers on tax matters surrounding the formation of, and investments by, private equity funds, credit funds, real estate funds and registered funds, among others. She also counsels sponsors on tax aspects related to a wide range of transactional matters, including continuation funds, GP stakes matters and portfolio company acquisitions and dispositions. In particular, she has deep experience advising sponsors and institutional investors on tax matters across real estate transactions, including public, private, equity and debt REITs.

John Terzaken - Partner A leading antitrust litigator and former federal prosecutor, John Terzaken is Global Co-Chair of the Firm’s Antitrust and Trade Regulation Practice. John represents corporate and individual clients involved in government enforcement of antitrust, fraud and other white collar violations, as well as related follow-on civil litigation. His experience spans market sector investigations and litigation in all major industries, including financial services, pharmaceutical, professional services, manufacturing, energy, shipping, food and beverage, and many others. John previously served as the Director of Criminal Enforcement of the Department of Justice, Antitrust Division, where he oversaw the Division’s criminal enforcement and litigation nationwide. He has earned awards of distinction from the Attorney General of the United States and the Assistant Attorney General for the Antitrust Division.

John was named as a 2022 “MVP” in Competition by Law360, and is consistently recognized as a leading antitrust lawyer (Band 1) by both Chambers Global and Chambers USA, where clients describe him as “. . . very strategic and creative with investigations,” “one of the strongest lawyers I have ever worked with,” “. . . a superb lawyer in the cartel space,” “highly professional and very responsive,” an attorney who is “extremely well respected,” “. . . smart, provides practical guidance and brings a lot to the table with his DOJ background,” “knows the technical aspects of antitrust law and also how to intuitively apply that to business realities,” and has a “wonderful working manner with clients and government figures.” John is also recognized in The Legal 500 “Hall of Fame,” where sources say he is “the very best of the best,” that he “brings unmatched knowledge, experience, relationships, attention to detail, responsiveness and wisdom to each engagement and interaction,” and that he “is equally comfortable speaking the language of law and the language of business.” He is recognized as a “Litigation Star” both nationally and in D.C. by Euromoney’s Benchmark Litigation and is also recognized by Who’s Who Legal: Competition.

Katharine L. Thompson - Partner

Based in Washington, D.C., Katharine Thompson is a Partner in the Firm’s Capital Markets Practice. Katharine represents corporate issuers, private equity sponsors and underwriters in a wide range of securities offerings, including initial public offerings and follow-on equity offerings, as well as spin-offs and high yield and investment grade debt offerings. Katharine also advises clients with regard to ongoing public reporting, compliance and corporate governance matters.

Malcolm J. (Mick) Tuesley - Partner Malcolm “Mick” Tuesley, Head of the Firm’s National Security Regulatory Practice, has significant experience representing clients in national security reviews before the Committee on Foreign Investment in the United States (CFIUS) and assisting clients with related issues, including mitigation of foreign ownership, control or influence (FOCI) under industrial security regulations; export control compliance; and government contracting. Mick has been involved with negotiating national security agreements for some of the largest and most complex transactions in the defense, energy, financial services, telecommunications and technology industries. Mick was named a Law360 “MVP” for International Trade in 2019. He is consistently recognized by The Legal 500, where sources call him “outstanding” and “an expert in FOCI mitigation issues and a creative problem solver.” He is also consistently recognized by Chambers USA (Band 1) and Chambers Global, where commentators note his “good sense of both CFIUS and corporate law.” Sources cite that Mick is “a very knowledgeable lawyer and can navigate tricky situations,” and “is one of the guiding lights of the CFIUS bar.” Mick currently serves on the Bladder Cancer Advocacy Network’s Board of Directors.

William H. Hinman - Senior Advisor

Former Director of the Securities and Exchange Commission’s Division of Corporation Finance, Bill Hinman focuses on a wide range of corporate and securities law matters—including some of the most significant initial public offerings in history. Bill also represents clients in connection with corporate acquisitions and governance matters. Widely recognized as a leading corporate law practitioner, Bill has extensive experience across an array of industries, including technology, e-commerce, digital assets, healthcare and life sciences. He played a lead role in the IPOs of Alibaba, Facebook, Google, eBay, Square, Agilent, Seagate and VMware, among many others.

During his tenure at the SEC between 2017 and 2020, Bill led the Division of Corporation Finance on a wide range of issues vital to the success of the nation’s capital markets.

Jonathan H. Pacheco - Senior Counsel

Jonathan Pacheco is Senior Counsel in the Firm’s Registered Funds Practice. Jonathan represents a wide array of registered funds, business development companies and multinational investment advisers on a broad range of corporate transactions. He regularly represents public funds, fund sponsors, investment advisers, investment banks and other financial institutions on a wide range of securities offerings, including initial public offerings, follow-on and secondary equity offerings, at-the-market programs, preferred equity offerings, and high yield and investment grade debt offerings, as well as exchange offers and other liability management transactions. Jonathan also advises clients on ongoing public reporting, compliance and corporate governance matters.

Maura L. Whelan - Senior Counsel

Maura Whelan is Senior Counsel in the Firm’s Exempt Organizations Practice. Maura provides philanthropists and philanthropic organizations of all types comprehensive and specialized advice honed from years of experience. Maura’s practice focuses on representing tax-exempt organizations, high net worth individuals, family offices, major corporations, and novel philanthropic structures in carrying out their philanthropic endeavors. She advises clients on a wide variety of structural and operational issues, including formation, governance, succession planning and compliance with applicable tax rules. Maura has particular experience working with private foundations and other grantmaking organizations to structure and implement complex grantmaking programs. She regularly counsels donors of major gifts, including gifts of art and other complex assets. Maura represents charitable and social welfare organizations making social impact and mission- and program-related investments, and endowments, foundations and other institutional investors making alternative investments.

Adrienne V. Baxley - Counsel Adrienne Baxley provides strategic counsel on significant government and internal investigations, and advises on a wide range of complex white collar criminal, regulatory enforcement and litigation matters. She represents clients in a broad spectrum of industries, including financial services, energy, technology, transportation and healthcare.

Gary E. Brooks - Counsel

Gary E. Brooks focuses his practice on the investment management industry, primarily working with registered investment companies (including open-end and closed-end funds) and business development companies, their investment advisers and boards on a wide range of transactional, regulatory, compliance and securities law matters. He has extensive experience advising asset management firms on the formation and operation of investment funds across the various types of registered fund structures, including open-end funds, interval funds, tender offer funds, listed closed-end funds, business development companies and exchange-traded funds.

Jeremy P. Entwistle - Counsel

Jeremy Entwistle counsels asset management firms on transactional and regulatory matters arising under the Investment Company Act of 1940 and other federal securities laws. Jeremy routinely advises on the formation, structuring, and regulation of business development companies and registered closed-end funds. In addition, Jeremy has significant experience in the distribution of non-traded investment products, including the negotiation of distribution agreements and related contractual arrangements.

Emily B. Holland - Counsel

Emily is a member of Simpson Thacher & Bartlett’s Sustainability and ESG Practice, based in the Washington D.C. office, and a five-time Chambers recognized practitioner in Global Business & Human Rights Law (including 2025). She advises the world’s leading business organizations, including financial institutions, private equity firms and public and private corporations, on novel and complex issues arising from an emerging area of law and regulation, competing stakeholder mandates, and evolving business priorities that impact companies’ ability to execute their ESG strategy and create long-term value. Her work covers matters relating to ESG and impact investing, sustainable finance debt offerings and credit facilities, securities offerings, mergers and acquisitions, disclosure and reporting, and ESG-related litigation. Emily has extensive experience advising on human rights matters across governance, due diligence, supply chain compliance, crisis management and remediation. She has also advised governments, intergovernmental organizations and NGOs on human and labor rights issues and the broader sustainability agenda. She is an Adjunct Professor of Law at Georgetown University Law Center.

Focusing primarily on social and governance matters, Emily aids her clients in navigating ESG risk across a variety of industries. She has also advised governments, intergovernmental organizations and NGOs on human and labor rights issues and the broader sustainability agenda.

Collin Janus - Counsel

Collin Janus leverages his private practice experience and his advisory roles at significant banks and financial institutions to counsel domestic and international financial institutions on the full spectrum of regulatory, transactional and enforcement matters. His work ranges from advising on complex acquisitions and investments to compliance and new activity matters. He routinely represents clients before federal regulators, including the Federal Reserve, OCC and FDIC, as well as U.S. state banking regulators.

Ashlie Lawton - Counsel

Ashlie advises clients on a broad array of executive compensation and employee benefits arrangements, particularly with regard to issues arising in the context of mergers and acquisitions, joint ventures, spin-offs, initial public offerings and other transactions. She regularly represents public and private companies, including executives and board members, on a range of compensation-related matters, including on the design, negotiation and implementation of employment agreements, equity compensation, performance incentives, deferred compensation, change in control protections and management participation in buyouts and new ventures. 

Ruoke Liu - Counsel

Adam S. Lovell - Counsel

Leveraging his experience in private practice and as a senior counsel in the SEC’s Division of Investment Management, Adam Lovell focuses his practice on a broad range of investment management issues related to registered funds, registered investment advisers and fund boards. He advises asset management firms on compliance with the Investment Company Act and the Investment Advisers Act, and on the operation of investment funds across various types of registered fund structures, including interval funds, listed closed-end funds and business development companies.

Matthew C. Micklavzina - Counsel

As Counsel in the Firm’s Registered Funds Practice, Matt Micklavzina focuses his practice on a broad range of investment management issues related to registered funds, registered investment advisers and fund boards. He has extensive experience advising asset management firms on the formation and operation of investment funds across various types of registered fund structures, including interval funds, tender offer funds, listed closed-end funds, business development companies, open-end funds and exchange-traded funds.

Jim Perry - Counsel

Jim Perry advises multinational corporations, private equity funds and financial institutions on a range of regulatory compliance concerns arising from business acquisitions and investments, including national security reviews, economic sanctions, anti-money laundering, and other regulatory concerns.

Ryan D. Stalnaker - Counsel

Ryan Stalnaker is Counsel in the Firm’s Litigation Department, and a member of the Firm’s National Security Regulatory Practice. Ryan’s practice focuses on the intersection of regulatory compliance and national security, and he advises corporations, financial institutions and private equity firms on regulatory and compliance issues, including: anti-bribery and corruption, economic sanctions, export controls, government contracts, transactional due diligence and national security reviews before the Committee on Foreign Investment in the United States (CFIUS).

Debra Wong Sutter - Counsel

Debbie Sutter is Counsel in Simpson Thacher’s Registered Funds Practice. Based in the Firm’s Washington, D.C. office, Debbie focuses on a broad range of investment management issues related to registered funds, registered investment advisers and fund boards. She advises asset management firms on the operation and formation of investment funds, including interval funds, listed closed-end funds and business development companies. 

Abigail W. Williams - Counsel