Steve Tonsfeldt


I work with companies on high-stakes, game-changing deals.

Steven Tonsfeldt represents public and private companies in domestic and cross-border M&A transactions, contested transactions, hostile takeovers and defense planning. He also advises private investors and their portfolio companies on investment and acquisition transactions, and financial advisors working with companies engaged in transactional matters.

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  • Amazon to Acquire One Medical for $3.9 Billion 

  • NeoPhotonics Agrees to Sell to Lumentum for $918 Million 

  • Tapjoy Agrees to Sell to ironSource 

  • Byju’s Agrees to Acquire Tynker to Continue US Expansion 

  • Genome Medical Closes $60 Million Series C Financing and Acquires GeneMatters 

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  • University of California, Berkeley School of Law

  • University of Iowa
    BBA, Accounting
    with highest distinction

Admissions & Credentials



  • Berkeley Center for Law and Business – Executive Advisory Board

  • Certified Public Accountant

Rankings & Accolades

    Lawdragon: 500 Leading Dealmakers in America (2021)

    Who's Who Legal: Thought Leaders – M&A and Governance (2021)

    Chambers USA: Corporate/M&A (California – San Francisco, Silicon Valley & Surrounds) (2002-2022)

    IFLR1000: Highly Regarded – Private Equity, M&A (California) (2020)

    American Lawyer: Dealmaker of the Week

    Best Lawyers in America: Mergers & Acquisitions (2006 – 2021)

    Legal 500: M&A (Large Deals) (2021)