Leslie J. Weiss

  • One North Wacker Drive
    Suite 4400
    Chicago, IL 60606-2833

Leslie J. Weiss is a partner in the Chicago office of Barnes & Thornburg LLP and the co-administrator of the firm’s Chicago Corporate Department.


Ms. Weiss focuses her practice on business transactions, general corporate representation and securities corporate law. She has developed a substantial corporate transactional practice focusing on entrepreneurs and the companies they build, finance, acquire and sell. Her practice includes growth companies, technology companies, medical device companies, internet based companies, communications companies, publicly traded companies, startups and participants in the financial services industry. Throughout her career Ms. Weiss has served as general counsel and legal advisor for numerous clients without in-house counsel.


Ms. Weiss’ experience includes the representation of private and public companies, both domestic and international, in their general corporate and securities work. She has led the teams on both the buy and sell sides for numerous mergers and acquisitions. 

She has also lead teams for many capital-raising transactions, including private equity investments, venture capital transactions and angel rounds. Ms. Weiss has represented clients in numerous venture rounds, with multiple venture firms located in various parts of the US participating in each round. Representation has been primarily on the company side, but includes fund representation as well. Ms. Weiss has experience with private and public offerings and 1934 Act securities compliance filings. She has also assisted her clients with complex intellectual property licensing deals.

Many of the transactions were cross border transactions and she has represented both the U.S. and non U.S. participants in these deals. 

From Start-Up to Exit

Ms. Weiss has represented many clients from the start-up phase through their ultimate exit, handling multiple financing rounds and acquisitions for those clients as well as general corporate counseling as the legal needs of those clients grew and became more complex. She has attended and guided clients in board meetings and understands the complexities of the relationships between founders and sophisticated investors. She has been instrumental in helping clients plan business expansions, which often involve significant restructuring and recapitalization of the clients’ entities. These experiences have given her a deep understanding of the needs of growing businesses, the impact the different interests of management and the boards of companies have on those businesses and the steps a business must take to prepare for a successful exit.

Financial Services Industry

During her entire career, Ms. Weiss has represented participants in the finance services industry, including broker-dealers, investment advisers, hedge funds and proprietary trading firms. She has assisted those clients with regulatory compliance matters, capital raising transactions and acquisitions. She has advised them on issues raised by regulatory audits and represented them in front of a number of different regulatory agencies, FINRA, NFA and various exchanges. Ms. Weiss has been working on legal matters affecting entities that trade derivatives listed since she started practicing law.


Ms. Weiss earned her B.A. in government and economics cum laude from Smith College, and her J.D. from Northwestern University School of Law. She is admitted to practice in the State of Illinois.

Ms. Weiss regularly judges and offers advice to new businesses presented by MBA candidates and other entrepreneurs.

Representative Experience

  • Sale of medical device company based offshore to publicly traded Chinese company for under $100 million.
  • Establishment of two separate offshore joint ventures engaged in the development of medical devices. 
  • Represented public company in sale of control to private equity firm. Continued ongoing representation of the company after the sale.
  • Represented public company in a $154 million bank financed corporate acquisition.
  • Represented buyer in purchase of component manufacturer for defense products.
  • Represented Dough, Inc. in $25 million Series B venture capital funding round. Represented the company in its Series A round earlier.
  • Represented licensor in $35 million licensing deal, which followed a $50 million development contract.
  • Represented DialogTech, Inc. in a $30 Series E round and the purchase of a competing business. Represented DialogTech, Inc. in its Series A through Series D financing rounds.
  • Represented technology company in $25 million A Round with Silicon Valley VC.
  • Formed and represented commodity pool for entrepreneurial sponsor that grew to just under 1 billion AUM.
  • Formed and represented investment fund to capitalize high frequency trading firm that is a significant player in the listed options market.
  • Set up joint venture for the operation of a broker-dealer with a joint back office arrangement.
  • Represented thinkorswim, Inc. from its formation to its sale to TD Ameritrade.
  • Represented client in complex multi-million dollar SEC action involving Regulation SHO.
  • Represented clients in regulatory matters involving the net capital rule.
  • Represented client in insider trading investigation by the SEC.