Companies large and small, domestic and foreign, turn to Jayun Koo for advice on securities law and general corporate matters. Jayun represents issuers, underwriters, and institutional investors in public and private securities transactions, including initial public offerings, follow-on offerings, ATMs, PIPEs, up-listing offerings, reverse mergers and other public company strategic transactions across a wide range of sizes and levels of complexity. She also handles SEC reporting and compliance and corporate governance matters and also regularly represents foreign issuers accessing the U.S. capital markets.

Emerging growth technology companies particularly appreciate Jayun’s understanding of their unique needs and her ability to provide tailored guidance and practical solutions to achieve their objectives. Jayun regularly operates as an outside general counsel for many of her clients, collaborating when necessary with the firm’s M&A, FDA, IP, Tech Transfer, Employee Benefits and Executive Compensation, and litigation teams.

Jayun’s clients also benefit from her experience and proactive approach. Her understanding of public companies’ responsibilities and disclosure requirements enables her to anticipate and address issues before they become concerns. With experience on both the issuer and underwriter side, she is especially adept at efficiently guiding clients through transactions subject to additional limitations and layers of restrictions imposed by the securities laws and the stock exchanges.

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Selected Client Representations
  • Represented VBI Vaccines in its successful underwritten public offering and concurrent registered direct offering of common shares for aggregate gross proceeds of approximately $71.9 million.
  • Represented a biotechnology company in its follow-on offerings involving preferred stock units and pre-funded warrants.
  • Represented the underwriter in an underwritten offering of units and pre-funded units.
  • Represented an Israeli specialty biopharmaceutical company in its public offering of American Depositary Shares.
  • Represented PhaseRx, Inc. in its initial public offering.
  • Private securities offerings and other securities transactions.
  • Reporting obligations under the Securities Exchange Act of 1934.
  • Preparation of registration statements on Forms S-8 and S-4.
  • Compliance with corporate governance best practices and regulations, such as: NYSE and NASDAQ requirements with respect to board composition, committee charters and other listing standards; State law governing shareholder meetings; and Disclosure committee. policies and charters, information disclosure policies; and enterprise risk management policies.
  • Preparation of securities filings, including Schedule 13D and Section 16 filings.
  • Mergers and acquisitions involving public and private entities.


J.D., Columbia Law School, 2010, Journal of Asian Law, Staff Editor

B.A., University of Pennsylvania, 2006, magna cum laude




New York

Press Release
Haynes and Boone Advises BioSig Technologies in $17.5 Million Offering
June 30, 2020

A Haynes and Boone, LLP deal team represented BioSig Technologies, Inc. (Nasdaq: BSGM) in a $17.5 million registered direct offering of its common stock, which closed on June 26, 2020. BioSig Technologies is a medical technology company commercializing a proprietary biomedical signal processing platform designed to improve signal fidelity and uncover the full range of electrocardiogram (ECG) and i [...]