Grobstein Teeple LLP

Biography

William Thomsen is a business valuation and economic damages professional with approximately 30 years of experience working with attorneys, CPAs, business owners, and advisory teams. He specializes in closely held and family-owned business valuation, ownership transitions, shareholder and partner matters, buy-sell agreements, internal transactions, succession planning, estate and gift tax valuation, acquisition evaluation, and valuation-related disputes.

William is often involved where professional judgment is central: reported financial results require interpretation, adjustments or normalization are needed, ownership interests are changing, or an independent valuation is required to support planning, negotiation, reporting, settlement, or litigation. He also provides economic damages analysis and expert support in matters involving lost profits, business value, shareholder disputes, partner separations, and other valuation-related claims.

His work includes U.S. clients and advisory teams operating between the U.S., the UK, and Europe, particularly where valuation issues intersect with tax, transactions, ownership planning, disputes, or cross-border advisory needs. He structures engagements with clear scope, defined phases, and practical communication so advisors and clients understand the process and cost as matters develop.

William holds the CFA designation and is an Accredited Senior Appraiser (ASA) with the American Society of Appraisers. He holds an MBA in Finance from Columbia Business School and a BA in Economics from Pomona College, which included economics study at Oxford University. He contributed a chapter on lost profits damages to Shannon Pratt’s The Lawyer’s Business Valuation Handbook and serves on the Editorial Board of The Value Examiner.