#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 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, 2,495 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.