David Westenberg is a partner in the Corporate Practice Group and the Capital Markets Group. He joined the firm in 1983.

Mr. Westenberg has focused on the software, Internet and information technology industries for more than twenty years, guiding numerous startup clients from formation through venture financing and on to successful acquisitions or IPOs. As outside corporate counsel to many public and private companies, Mr. Westenberg advises clients on a wide variety of corporate, securities, disclosure and governance matters. His transactional experience includes more than 50 IPOs and other capital markets transactions, as well as a large number of venture capital financings and M&A transactions. He is the author of Initial Public Offerings: A Practical Guide to Going Public (Practising Law Institute), a comprehensive yet practical guide to the IPO process that has been hailed for its unprecedented breadth, depth and ease of use and was dubbed the "bible of the IPO market" by The New York Times (The Deal Professor, January 19, 2010).


The Road to IPO: Legal and Regulatory Insights into Going Public blog focuses on IPOs, including legal and regulatory developments affecting the IPO market, analysis of market practices, and information of interest to all companies planning or hoping to go public. Blog host David Westenberg, a partner in the firm’s capital markets group, is one of the country’s foremost authorities on IPOs. He writes and is quoted frequently on the IPO market, and is the author of the acclaimed book, Initial Public Offerings: A Practical Guide to Going Public.

Professional Activities

Mr. Westenberg is active in various technology councils and is a former co-chair of the Corporate Law Committee of the Boston Bar Association.

Mr. Westenberg writes frequently on the IPO and venture capital markets, and has been quoted or featured in The American Lawyer, Boston Business Journal, The Boston Globe, Boston Magazine, TheCorporateCounsel.net, CFO.com, Investor’s Business Daily and The Wall Street Journal.

  • Initial Public Offerings: A Practical Guide to Going Public

    The ultimate roadmap to the IPO process. Hailed by executives, entrepreneurs, general counsel, investment bankers and venture capitalists alike as the definitive IPO guide, this comprehensive resource charts every twist and turn on the IPO journey and provides battle-tested, real-world advice on how to navigate the roadblocks to reach your destination—a winning IPO.

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  • 2022 IPO, Venture Capital and M&A Reports

    WilmerHale’s annual IPO, Venture Capital and M&A reports provide insights into market conditions, as well as comprehensive statistics and analysis that are hard to find elsewhere.

    February 28, 2022
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    • Dynatrace's $655 million IPO and follow-on public offerings raising a total of $3.88 billion (underwriters’ counsel)
    • EverQuote's $84 million IPO
    • Casa Systems' $90 million IPO and $184 million follow-on public offering
    • Blue Apron's $300 million IPO, $37 million follow-on public offering and $78 million equity capital raise
    • Acacia Communications' $119 million IPO and $517 million follow-on public offering
    • Sale of Gilt Groupe to Hudson's Bay Company for $250 million
    • HubSpot's $144 million IPO and $167 million follow-on public offering (underwriters' counsel)
    • Imprivata's IPO raising $86 million (underwriters' counsel)
    • Endurance International Group's IPO raising $252 million and follow-on public offerings raising a total of $479 million
    • Late-stage and crossover financings for various clients, including Blue Apron ($135 million) and Gilt Groupe ($50 million)
    • SS&C Technologies Holdings' IPO and follow-on public offerings raising an aggregate of more than $1.4 billion
    • Bottomline Technologies' follow-on public offerings of common stock and convertible senior notes raising a total of more than $250 million
    • Kiva Systems' acquisition by Amazon.com for $775 million
    • Brightcove's IPO raising $63 million (underwriters' counsel)
    • Tangoe's $101 million IPO and $170 million follow-on public offering
    • Accretive Health's $138 million IPO and $175 million follow-on public offering
    • Netezza's acquisition by IBM for $1.7 billion
    • "Dual track" IPO/sale for EqualLogic, resulting in $1.4 billion acquisition by Dell—the largest cash purchase price in history for a private VC-backed company
    • "Dual track" IPO/sale for McLeodUSA, resulting in $557 million acquisition by PAETEC Holding
    • Sale of MapInfo to Pitney Bowes for $472 million
    • Cynosure's IPO raising $86 million
    • Sale of MatrixOne to Dassault Systèmes for $408 million
    • Avid's acquisition of Pinnacle Systems for $462 million
    • Prodigy's IPO (then the largest Internet company IPO in history) and its $1.6 billion strategic transaction with SBC Communications
    • Venture capital financings for various clients


  • Award Text

    Leading Lawyer for Corporate/M&A: Capital Markets

    Chambers USA


  • Award Text

    Boston's Information Technology Law Lawyer of the Year for 2015, 2019 and 2021 & Technology Law Lawyer of the Year for 2012, 2018, 2020 and 2022

    Best Lawyers in America®

    2012, 2015, 2018-2022

  • Award Text

    Outstanding Authoritative Book by a Partner in a Law Firm

    The Burton Foundation


  • Recognized as a leader for Corporate/M&A: Capital Markets in the 2013–2022 editions of Chambers USA: America's Leading Lawyers for Business
  • Recommended in the 2016–2019 editions of The Legal 500 United States for finance: capital markets: equity offerings: advice to issuers
  • Mr. Westenberg's book, Initial Public Offerings: A Practical Guide to Going Public, received the 2013 "Outstanding Authoritative Book by a Partner in a Law Firm" award, given annually by the Burton Foundation to one book that represents "an important contribution to the legal profession" and "is comprehensive in scope, informative, incisive, and is an important reference and informational tool" 
  • Named by Best Lawyers in America as Boston's Technology Law Lawyer of the Year for 2022, 2020, 2018 and 2012 and Boston's Information Technology Law Lawyer of the Year for 2021, 2019 and 2015, and is consistently ranked as one of the Best Lawyers in America in the areas of corporate, information technology, mergers & acquisitions, venture capital and technology law
  • WilmerHale's IPO, Venture Capital and M&A Reports, co-authored by Mr. Westenberg, received a Best Law Firm Publication Award given by the Burton Foundation in 2006 for excellence in legal writing 
  • Named in Boston Magazine as a "New England Super Lawyer" (formerly "Massachusetts Super Lawyer") each year since 2004 
  • Selected by American Lawyer magazine as "Dealmaker of the Year" for equities (2001)
  • Named an "All Star for Law & Technology" by Mass High Tech for fostering the development of New England technology companies (1999)

Insights & News


  • Education

    • JD, Harvard Law School, 1983

    • SB, Massachusetts Institute of Technology, 1979

  • Admissions

    • Massachusetts