ALXN Alexion Pharmaceuticals Inc

Alexion Pharmaceuticals, Inc. 2000 Stock Option Plan

Alexion Pharmaceuticals, Inc. 1992 Stock Option Plan for Outside Directors

Alexion Pharmaceuticals, Inc. 1992 Stock Option Plan

Portola Pharmaceutical, Inc. Amended and Restated Inducement Plan

Portola Pharmaceutical, Inc. 2013 Equity Incentive Plan

Synageva BioPharma Corp. 2014 Equity Incentive Plan

Prolifarion, Inc. 1999 Long Term Incentive and Stock Option Plan

(Full titles of the plans)

David E. White

Treasurer
Alexion Pharmaceuticals, Inc.
1800 Concord Pike

Wilmington, DE 19850
(Name and address of agent for service)

(302) 886-6994
(Telephone number, including area code, of agent for service)

With copies to:

Sebastian L. Fain

Freshfields Bruckhaus Deringer US LLP

601 Lexington Avenue, 31st Floor

New York, New York 10022

1-212-277-4000

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ¨

DEREGISTRATION OF COMMON STOCK

This Post-Effective Amendment (the “Post-Effective Amendment”), filed by Alexion Pharmaceuticals, Inc., a Delaware corporation (f/k/a AstraZeneca Rare Disease Holdings Inc., f/k/a Delta Omega Sub Holdings Inc.) (the “Registrant”) and successor in interest to Alexion Pharmaceuticals, Inc., a Delaware corporation (the “Company”), relates to the following registration statements on Form S-8 (each as amended, the “Registration Statements”) (including one registration statement on Form S-4 amended by post-effective amendment no. 1 thereto on Form S-8) of the Company, previously filed with the Securities and Exchange Commission (the “Commission”):

On December 12, 2020, AstraZeneca PLC (“AstraZeneca”), the Registrant, the Company, Delta Omega Sub Holdings Inc. 1, a direct, wholly owned subsidiary of the Registrant (“Merger Sub I”) and Alexion Rare Disease LLC (f/k/a Delta Omega Sub Holdings LLC 2), a direct, wholly owned subsidiary of the Registrant (“Merger Sub II”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) that provided for the acquisition of the Company by AstraZeneca. On the terms and subject to the conditions set forth in the Merger Agreement, on July 21, 2021 (1) Merger Sub I merged with and into the Company (the “First Merger”) with the Company surviving the First Merger as a wholly owned subsidiary of the Registrant, and (2) immediately following the effective time of the First Merger, the Company merged with and into Merger Sub II (the “Second Merger”) with Merger Sub II surviving the Second Merger as a direct wholly owned subsidiary of the Registrant and an indirect wholly owned subsidiary of AstraZeneca. Effective on July 22, 2021, Merger Sub II merged with and into the Registrant, at which point the Registrant’s name was changed from AstraZeneca Rare Disease Holdings Inc. to Alexion Pharmaceuticals, Inc. (such merger, together with the First Merger and the Second Merger, the “Mergers”).

As a result of the Mergers, any offering pursuant to the Registration Statements has been terminated and the Registrant hereby terminates the effectiveness of the Registration Statements. In accordance with an undertaking made by the Company in the Registration Statements to remove from registration, by means of a post-effective amendment, any of the securities registered under each Registration Statement that remain unsold at the termination of the offerings, the Registrant hereby removes from registration the securities registered but unsold under the Registration Statements, if any.