Katharine Moir

Simpson Thacher & Bartlett LLP

$ $$$

Hanover Street 2475
Palo Alto 94304 CA US

Katharine P. Moir heads the Tax Practice in Simpson Thacher’s Palo Alto office, providing clients with tax advice in a broad range of transactions, including mergers, acquisitions, joint ventures, formation of private investment funds, and securities offerings. Katharine’s clients include private equity firms such as Hellman & Friedman, Silver Lake Partners, KKR, and Warburg Pincus, as well as leading technology companies such as Alibaba, Dell, and Microsoft.

Katharine was the lead tax partner for the following transactions:

  • Dell in its $67 billion acquisition of EMC, the largest technology deal to date
  • Silver Lake Partners and GIC in their $2.6 billion strategic investment in Ancestry.com
  • KKR in its $1.2 billion sale of Alliance Tire Group to Yokohama Rubber
  • Interactive Data Corporation in its $5.2 billion acquisition by Intercontinental Exchange
  • Silver Lake in the establishment of Silver Lake Partners IV, L.P., with $10.3 billion in total commitments, the largest amount ever raised for a technology investment-focused private equity fund
  • Yahoo! in its acquisition of Tumblr

Katharine is recognized as a leading tax lawyer by Chambers USA: America’s Leading Lawyers for Business, which noted “She is acclaimed as very knowledgeable and easy to work with. She understands what the client wants, and is practical at getting a deal done.” Recent speaking engagements have included Practising Law Institute’s “Tax Planning for Domestic & Foreign Partnerships, LLCs, Joint Ventures & Other Strategic Alliances” and the TEI-San Jose State High Tech Tax Institute’s “What’s New in High Tech Mergers and Acquisitions.”

Katharine received her B.A. with honors from Princeton University in 1992 and her J.D. with honors from the University of Chicago in 1996, where she was elected to the Order of the Coif. She is admitted to practice in California, New York and Illinois.


  • University of Chicago Law School, 1996 J.D.
    • with honors; Order of the Coif; University of Chicago Law Review, 1994–1996
  • Princeton University, 1992 A.B.
    • with honors


  • Illinois 1996
  • New York 1998
  • California 2002


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Hanover Street 2475
Palo Alto 94304 CA US
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Lina Stillman

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New York 10006 NY US