Simin Sun assists clients in connection with complex mergers and acquisitions (both on the buyer and seller side), especially those that contain a technology or international component, and corporate securities matters, especially those that involve capital raises through public or private equity or debt. He also advises on general corporate matters and strategic planning.

Simin has represented clients in transactions in jurisdictions within the U.S., Asia, Europe, the Middle East, and the Caribbean. Whether the client is a public or private company focused on energy, biotechnology, software, chemical manufacturing, or distribution, Simin is able to provide insightful legal advice to help a transaction reach a satisfactory conclusion for his clients.

Simin is an innovative problem solver with a reputation for providing high-quality legal services and finding creative solutions to resolve difficult problems. He enjoys working directly with owners and founders of companies, particularly in the technology space, and has extensive experience advising startups, venture capital funds, entrepreneurs, and middle-market companies with their first major financing round. Simin’s clients value the deeply personal, genuine relationships he forms with them, that extend beyond mere business problem-solving.

Simin is a member of the Houston Association for Corporate Growth and the Association of Corporate Counsel. He previously served as an Ambassador for the Houston Bar Association. 

Selected Publications

  • "Sign & Consent: A Review of Customary Deal Terms in an Openlane Transaction" HBA Seminars Series, October 20, 2017
  • "Damages Limitations in NDAs and Confidentiality Agreements," co-author with Debra Hatter, January 2012.
Show More
Expand All
  • WuXi Pharmatech in its $65 million acquisition from NextCode Health named Best US Technology Deal of 2015 by Acquisition International.
  • Nabors Industries in its acquisition of Robotic Drilling Services AS.
  • Represented QuestaWeb in its sale to Descartes Systems Group.
  • Investment by a subsidiary of a Chinese state-owned entity in an osmosis technology company.
  • Represented Applied Optoelectronics, Inc., designer and manufacturer of advanced optical products, in a Rule 144A private placement offering of $80.5 million aggregate principal amount of 5.00 percent Convertible Senior Notes due 2024.
  • Represented Callon Petroleum Company, a public oil and gas company, in its private offering of $400 million aggregate principal amount of 6.375 percent senior unsecured notes due 2026.
  • Represented Endeavor Energy Resources, L.P. in a public offering of $300 million senior notes.
  • Represented Endeavor Energy Resources, L.P. in a tack-on public offering of $250 million senior notes.
  • Roll-over of a U.S. minority-owned business in camera distribution to a private equity buyer.
  • NYSE-listed company in establishing a manufacturing business in Japan. 


J.D., University of Pennsylvania Law School, 2011, Asian Pacific American Law School Students Association; East Asia Law Review, Associate Editor; Constitutional Law Review, Associate Editor

B.B.A., Corporate Finance and Business Honors Program, University of Texas at Austin, 2008


Judicial Intern, The Honorable Judge Lee H. Rosenthal, U.S. District Court for the Southern District of Texas, Summer 2009


Chinese (Mandarin)



Press Release
Haynes Boone Represents Clinigen Limited in Acquisition of Drug Safety Navigator
December 02, 2022

A Haynes and Boone, LLP deal team represented Clinigen Limited in its acquisition of Drug Safety Navigator Inc. (DSN), a specialist pharmacovigilance service provider based in the U.S. A global pharmaceutical services company focused on providing ethical access to medicines, Clinigen said the acquisition enables it to add vital pharmacovigilance capabilities to its services offering for pharmaceut [...]