MARK K. CASTIGLIA is a partner in Sidley’s Century City office and is a member of the Private Equity and M&A practices. His practice focuses on advising private equity sponsors and their portfolio companies in all stages of the life cycle of a private equity investment, which includes advising on acquisitions, divestitures, restructurings and general corporate matters. Mark handles a wide range of transactions including stock and asset purchases, mergers, carve-out acquisitions and divestitures, equity financings and structured equity transactions. Mark also advises private equity sponsors on joint transactions and structured minority investments in partnership with other investment sponsors.

Partner
Mark K. Castiglia
- M&A
- Private Equity
Experience
- Representative Matters
- RSA Conference Parent (RSAC), backed by Clearlake Capital Group, L.P and Symphony Technology Group, in its spinoff from RSA Security, and Crosspoint Capital Partners’ acquisition of a significant interest in RSAC, which will become a stand-alone company.
- Clearlake Capital Group- and TA Associates-backed DigiCert, Inc., a provider of TLS/SSL, PKI, and IoT solutions, in a strategic investment by Crosspoint Capital Partners, L.P.
- Attralus, Inc., a clinical stage biopharmaceutical company focused on developing therapies to improve the lives of patients with systemic amyloidosis, in the close of its US$116 million Series B Preferred Stock financing
- Clearlake Capital Group, L.P. in its acquisition of Confluence Technologies, Inc. from TA Associates
- Precisely, a portfolio company backed by Clearlake Capital Group, L.P., in its acquisition of Winshuttle
- Symplr Software, a portfolio company backed by Clearlake Capital Group, L.P., in its proposed acquisition of HealthcareSource HR Inc., a provider of talent management software for the healthcare industry, from Francisco Partners
- Clearlake Capital Group, L.P. in its equity investment in RSA Security LLC, a global provider of mission critical cybersecurity software and governance risk and compliance management software solutions to enterprises
- Ivanti, Inc., a portfolio company backed by Clearlake Capital Group, L.P., in a strategic investment by Charlesbank Capital Partners, LLC
- Clearlake Capital Group, L.P. in its acquisition of Precisely, a global leader in data integrity, together with TA Associates
- Symplr, a portfolio company backed by Clearlake Capital Group, L.P., in its acquisition of Phynd Technologies, a global healthcare governance, risk management, and compliance software-as-a-service (SaaS) platform
- Ivanti, Inc., a portfolio company backed by Clearlake Capital Group, L.P., in its proposed acquisition of Cherwell Software, a provider of IT service management and enterprise management solutions
- Zywave, Inc., a leading Software-as-a-Service (SaaS) provider of front office distribution solutions backed by Clearlake Capital Group, L.P. and Aurora Capital Partners in its acquisition of Insurance Technologies Corporation (ITC), a provider of marketing, rating and management software and services to the insurance industry, from Accel-KKR
- Clearlake Capital Group, L.P. in its US$3 billion acquisition of Endurance International Group Holdings, Inc., a provider of cloud-based platform solutions designed to help small- and medium-sized businesses succeed online
- Dude Solutions Inc., a Software-as-a-Service (SaaS) provider of cloud-based operations management software backed by Clearlake Capital Group, L.P., in the acquisition of the asset management platform Confirm from Precisely
- Clearlake Capital Group, L.P. in its acquisition of Zywave, Inc., a Software-as-a-Service (SaaS) provider of front office insurance solutions
- ConvergeOne, a global IT services provider of collaboration and digital infrastructure solutions, in its acquisition of Altivon, a contact center solutions provider
- Clearlake Capital Group, L.P. in its new lead investment, together with funds managed by Blackstone Tactical Opportunities, in Diligent Corporation, an Insight Partnersportfolio company
- Perforce Software Inc. in its acquisition of Methodics Holdings Inc., a leading provider of intellectual property lifecycle management and traceability solutions
- Drunk Elephant, LLC in its US$845 million sale to Shiseido America Corporation
- Palo Alto Networks, Inc. in its US$410 million acquisition of cloud native security platform, Twistlock
- NetDocuments Software in an equity investment by Cove Hill Partners, L.P.
- Dwayne Johnson, Dany Garcia and certain of their affiliates in connection with a joint venture with IMG to launch Athleticon, a multi-day live event focused on athletics, wellness, and entertainment
- Empire Resorts, Inc. in its strategic alliance with bet365 to develop a physical and online sportsbook at Resorts World Catskills
- Zuffa, LLC and its subsidiary, Ultimate Fighting Championship, in its US$4.2 billion sale
- Eldorado Resorts, Inc. in connection with its definitive agreement for William Hill PLC to act as Eldorado’s exclusive sports betting operator
- Eldorado Resorts, Inc. on its acquisition of Tropicana Entertainment, Inc. in a US$1.85 billion cash transaction and master lease of the Tropicana real estate with Gaming and Leisure Properties
- The Special Committee of the board of directors of Westinghouse in connection with the sale of the Westinghouse business to Brookfield for approximately US$4.6 billion in cash and assumed liabilities
- Founding partners in their investment in Black Knight Sports & Entertainment Holdco, the vehicle formed to acquire the Vegas Golden Knights National Hockey League (NHL) expansion franchise
*Some of the above matters were handled prior to joining Sidley.
News & Insights
Credentials
Admissions & Certifications
- California
- New York
Education
- Columbia Law School, J.D., 2012 (Harlan Fiske Stone Scholar)
- Colgate University, B.A., 2009 (magna cum laude)