Sean M. Sweeney
Shareholder
Phone: (414) 755-5020
Fax: (414) 271-3841
E-mail: sms@hallingcayo.com
Areas of Practice:
Bar Admissions:
- Wisconsin State Court – Circuit, Appellate, and Supreme Court
- U.S. Federal District Court – Eastern District of Wisconsin
- U.S. Federal District Court – Western District of Wisconsin
- U.S. Federal Bankruptcy Court – Eastern District of Wisconsin
- U.S. Federal Appellate Court – 7th Circuit Court of Appeals
- U.S. Federal District Court – Northern District of Illinois
- U.S. Federal District Court – Eastern District of Michigan
Sean M. Sweeney’s practice focuses on business litigation, civil litigation, and stock broker fraud. Sean has experience litigating business and civil disputes as both plaintiff’s and defendant’s counsel as well as representing investors to recover their losses from misconduct by their investment advisors. He has been recognized in Best Lawyers since 2024 for his work in securities litigation.
Sean earned his Juris Doctor (JD) and Masters of Business Administration (MBA) from Marquette University. He earned his Bachelor of Science Degree in Business Economics from Northern Arizona University.
Sean and his team offer Transparent Fee Litigation on complex business litigation cases. Learn more about Transparent Litigation Pricing for business litigation. He also runs The Securities Lawyers, in which Halling & Cayo’s Securities Litigation team discusses securities fraud, stockbroker employment disputes, and FINRA arbitration.
Education:
- MARQUETTE UNIVERSITY LAW SCHOOL– Juris Doctor – May 2007
Thomas Moore Law Scholarship
Sports Law Review, Editorial Staff
Universidad de Costa Rica; San Jose, Costa Rica- Summer 2005
Universitaria San Pablo CEU; Madrid, Spain- Summer 2006 - MARQUETTE UNIVERSITY GRADUATE SCHOOL OF BUSINESS – Masters of Business Administration – May 2007
Computer Information Systems Training
SAS Business Intelligence Software
EViews Quantitative Micro Software - NORTHERN ARIZONA UNIVERSITY SCHOOL OF BUSINESS – Bachelor of Science in Economics – May 2004
Dean’s List: Spring 2001, Spring 2002, Fall 2002, and Fall 2003
Centennial Scholarship
National Student Exchange: Towson University; Towson, Maryland- Fall 2003
Honors and Awards:
In 2024, 2025, 2026 he was named as a Super Lawyer for Securities Litigation. No more than 2.5% of the lawyers in the state are selected to the list.- In the 2024, 2025, and 2026 edition of Best Lawyers in America®, Sean has been recognized for his excellence in Litigation – Securities. Recognition by Best Lawyers is based entirely on peer review.
- In 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, and 2022 Sean was named to the Wisconsin Super Lawyers® Rising Stars list as one of the top young attorneys in Wisconsin.
- In 2012, 2013, 2014, and 2015 Sean was named to M: Milwaukee’s Lifestyle Magazine’s Leading Lawyers for Litigation. Leading Lawyers only selects those attorneys ranked in the top 2-5% for each category.
- In 2013, Sean was named to the Wisconsin Law Journals selection of Up-And-Coming Lawyers. Honorees are nominated by colleagues and selected by Wisconsin Law Journal editorial staff.
- Sean maintains a rating of 10.0 “Superb” from Avvo.com. The rating is calculated using a mathematical model that considers elements such as years of experience, board certification, education, disciplinary history, professional achievement, and industry recognition.
In 2024, 2025, 2026 he was named as a Super Lawyer for Securities Litigation. No more than 2.5% of the lawyers in the state are selected to the list.
In 2013, Sean was named to the Speaking Engagements:
- Ethically Managing your Case Load, PIABA Annual Conference (2023)
- Wisdom of the Crowd, PIABA Annual Conference (2022)
- Motions to Dismiss – Eligibility and Statute of Limitations, PIABA Annual Conference (2021)
- The Whole Picture – Maximizing Damages in Securities Cases, PIABA Annual Conference (2021)
- Effectively Representing Client Issues in a Public Forum: Payment of Awards, Fiduciary Duty, and Forum Selection, PIABA Mid-Year Conference (2019)
- Congressional Process: How a Bill Becomes a Law, PIABA Mid-Year Conference (2019)
- Do’s and Dont’s of Group Arbitration Claims, PIABA Annual Conference (2017)
- LLCs From a Litigator’s Prospective – Avoiding Litigation, Lorman Education Services (2013)
- LLCs From a Litigator’s Prospective – Resolving Litigation, Lorman Education Services (2013)
- Investment Fraud, from Wall Street to Main Street, Milwaukee Bar Association Presents (2012)
- FINRA Mediation and Arbitration, State Bar of Wisconsin Litigation, Dispute Resolution & Appellate Practice Institute (2012)
- Hidden Gems in Adobe Acrobat, Wisconsin Solo and Small Firm Conference (2011)
- Ethics of Social Media, Wisconsin Solo and Small Firm Conference (2010)
- Using Blogging as an effective communication tool, Wisconsin Bar Leaders Conference (2009)
- Negotiating the Transition from Law School to Practice, Marquette University (2008)
Professional Associations and Memberships:
- Wisconsin Bar Association – Wisconsin Bar Litigation Section
- Wisconsin Bar Association – Wisconsin Bar Business Law Section
- Milwaukee Bar Association
- National Sports Law Institute
- Public Investors Arbitration Bar Association (PIABA)