X0306 4 2017-09-19 0 0001078075 NETSCOUT SYSTEMS INC NTCT 0001189174 EGAN JOHN R C/O NETSCOUT SYSTEMS, INC. 310 LITTLETON ROAD WESTFORD MA 01886 1 0 0 0 Common Stock 2017-09-19 4 M 0 4741 A 77504 D Restricted Stock Unit 2017-09-19 4 M 0 4741 D 2017-09-19 Common Stock 4741 0 D Restricted Stock Unit 2017-09-19 4 A 0 4236 A Common Stock 4236 4236 D The shares of Common Stock were acquired upon the vesting of certain restricted stock units previously granted to the reporting person. Price is N/A. Date is N/A. All of the Restricted Stock Units vest on the date of the Company's Annual Meeting to occur in 2018, provided that during the period from the date of grant through the date of such Annual Meeting, the reporting person attends at least 75% of the meetings, collectively, of the Board and any committee of the Board of which the reporting person is a member. In the event that the attendance requirements are not met, the Restricted Stock Units will not become vested until 09/19/2020. /s/ Greg Sloan, by Power of Attorney 2017-09-21