Tamar Kaplan-Marans focuses her practice on securities litigation and enforcement matters. She regularly represents issuers from a variety of industries in securities litigation matters, including securities class actions, shareholder derivative suits and merger disputes. She also counsels companies and their officers and directors when faced with allegations of breach of fiduciary duty and other alleged corporate governance issues.

Ms. Kaplan-Marans has experience with internal investigations and regulatory investigations conducted by the US Securities and Exchange Commission and the Department of Justice. She has represented companies in the financial services and accounting sectors in high-stakes enforcement matters related to insider trading, auditing and independence issues, securities lending and consumer financial laws.

Ms. Kaplan-Marans also maintains an active pro bono practice, including in the areas of immigration law, prisoners’ rights and the First Amendment.

Prior to joining WilmerHale, Ms. Kaplan-Marans served as a law clerk for the Honorable David Trager and as a judicial intern for Judge Joseph Bianco of the US District Court for the Eastern District of New York.


  • Successfully argued in New York Supreme Court’s Commercial Division for the dismissal with prejudice of breach of fiduciary duty claims against company and its directors arising out of a loan agreement. Arena Vantage SPV, LLC v. CoVenture-Vantage Credit Opportunities GP, 202 N.Y.S.3d 724 (N.Y. Sup. Ct. 2024).
  • After extensive briefing and multiple complaint filings, obtained dismissal of securities class action alleging that technology company made false statements and omissions concerning its projections of annual revenue, internal controls and other issues. Lefkowitz et al. v. Synacor, Inc., et al., 2019 WL 3553999 (S.D.N.Y. Aug. 28, 2019). The dismissal was affirmed by the Second Circuit in late 2020. Shreiber v. Synacor, Inc., 832 Fed. Appx. 54 (2nd Cir. Oct. 22, 2020).
  • Successfully represented an aerospace manufacturing company in securities litigation and enforcement matters arising out of restatements of its financial results. 
  • Obtained the dismissal of a securities class action complaint arising out of an alleged failure to disclose a Form 483 letter after an FDA inspection of an overseas contract manufacturing facility for a developer of an antibiotic. Schaeffer v. Nabriva Therapeutics PLC, No. 19-cv-04183-VM, 2020 WL 7701463 (S.D.N.Y. Apr. 28, 2020). After an amended pleading was later filed, the case was then favorably resolved.
  • Represented Apollo Education Group in a securities class action lawsuit filed against it based on the University of Phoenix's military recruiting practices and its transition to a new online learning platform. The initial amended complaint was dismissed without prejudice, Lomingkit v. Apollo Education Group, Inc., 2017 WL 3172861 (D. Ariz. 2017), and after repleading, was then dismissed with prejudice, 2017 WL 633148 (D. Ariz. 2017).
  • Represented leading broker-dealer in FINRA arbitration arising out of Puerto Rico municipal bond market crash of 2013. After a two-week trial in which the claimant sought $70 million in damages, secured a final award in the client’s favor, rejecting all claims brought by the claimant. 
  • Following a three-day bench trial in the Southern District of New York, obtained dismissal of a lawsuit brought under the Hague Convention on the Civil Aspects of International Child Abduction on behalf of a domestic violence victim. Ermini v. Vittori, 2013 WL 1703590 (S.D.N.Y. Apr. 19, 2013). The dismissal was later affirmed by the Second Circuit in a decision that described the case as involving “novel and significant issues” of “first impression.”  758 F. 3d 153 (2d Cir. 2014).


  • Honored in 2013 and 2014 with the Above & Beyond Award for Excellence in Pro Bono Advocacy by Sanctuary for Families. 

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  • Education

    • JD, Brooklyn Law School, 2009

      cum laude Executive Notes and Comments Editor, Brooklyn Law Review
    • BA, English, Columbia University, 2004

  • Admissions

    • New York

  • Clerkships

    • The Hon. David Trager, US District Court for the Eastern District of New York, 2009 - 2010



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