#1 Shares acquired on vesting of Performance Stock Units previously granted on February 28, 2018 under the 2017 Stock Incentive Plan.

#2 This sale was made to cover withholding taxes immediately following the vesting of previously granted Performance Stock Units.

#3 This sale was made to cover withholding taxes immediately following the vesting of previously granted Restricted Stock Units.

#1 Shares acquired on vesting of Performance Stock Units previously granted on February 28, 2018 under the 2017 Stock Incentive Plan.

#2 This sale was made to cover withholding taxes immediately following the vesting of previously granted Performance Stock Units.

#3 This sale was made to cover withholding taxes immediately following the vesting of previously granted Restricted Stock Units.

#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").

#1 This transaction was executed in multiple trades through a broker-dealer at prices ranging from $157.75 - $157.79. The price reported in this column reflects the weighted average sales price. Upon request, the reporting person will provide to the SEC staff full information regarding the number of shares sold at each price.