9999999995-19-000278 EFFECT 1 20190214 20190215 20190214 Stealth BioTherapeutics Corp 0001696396 2834 000000000 E9 1231 EFFECT 33 333-229509 19609747 275 GROVE STREET SUITE 3-107 NEWTON MA 02446 617-600-6888 275 GROVE STREET SUITE 3-107 NEWTON MA 02446 EFFECT 1 primary_doc.xml UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 NOTICE OF EFFECTIVENESS Effective Date: February 14, 2019 4:30 P.M. Form: F-6 CIK: 0001696396 Company Name: Stealth BioTherapeutics Corp File Number: 333-229509