#1 Disposed of in connection with the transactions contemplated by the Agreement and Plan of Merger, dated as of March 5, 2022 (the "Merger Agreement"), by and among the Issuer, Camelot Return Intermediate Holdings, LLC ("Parent") and Camelot Return Merger Sub, Inc. ("Merger Sub"), pursuant to which Merger Sub was merged with and into the Issuer (the "Merger"), with the Issuer surviving the Merger as a subsidiary of Parent (the "Surviving Corporation").

#2 At the effective time of the Merger (the "Effective Time"), in accordance with the Merger Agreement, each share of Issuer common stock, par value $0.01 per share (a "Share") outstanding immediately prior to the Effective Time of the Merger (other than certain excluded shares), was converted into the right to receive cash in an amount equal to $24.65 in cash per Share (the "Merger Consideration"), without interest and subject to any required withholding taxes. As a result of the Merger, the reporting person no longer beneficially owns, directly or indirectly, any Shares.

#1 Represents shares of Alexion common stock disposed in connection with the Agreement and Plan of Merger (the "Merger Agreement") dated as of December 12, 2020, by and among Alexion and AstraZeneca PLC. In accordance with the Merger Agreement, upon the First Effective Time (as defined in the Merger Agreement), each share of Alexion common stock was converted into the right to receive (i) 2.1423 American Depositary Shares (ADSs) of AstraZeneca PLC and (ii) $60.00 in cash (the "Merger Consideration"). Upon the First Effective Time, 2,635 restricted stock units were fully vested and cancelled and converted into the right to receive the Merger Consideration with respect to each share of Alexion common stock subject to such restricted stock units.

#1 Award of Restricted Stock Units under the 2017 Incentive Plan. Shares issuable pursuant to the Restricted Stock Units vest in their entirety on the first anniversary of the grant date.

#2 Award of Restricted Stock Units under the 2017 Incentive Plan. Shares issuable pursuant to the Restricted Stock Units vest as to 25% on a quarterly basis. These Restricted Stock Units were issued in lieu ofthe annual cash retainer that the director was entitled to receive for service as a director.

#1 Award of Restricted Stock Units under the 2017 Incentive Plan. Shares issuable pursuant to the Restricted Stock Units vest in their entirety on the first anniversary of the grant date.

#2 Award of Restricted Stock Units under the 2017 Incentive Plan. Shares issuable pursuant to the Restricted Stock Units vest as to 25% on a quarterly basis. These Restricted Stock Units were issued in lieu ofthe annual cash retainer that the director was entitled to receive for service as a director.