X0202 4 2006-08-15 0 0001292470 NightHawk Radiology Holdings Inc NHWK 0001239366 CHUNG PETER Y C/O SUMMIT PARTNERS 222 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116 1 0 0 1 Indirect GP of 10% Owner Common Stock 2006-08-15 4 J 0 900000 D 4500000 I See Footnote and Remarks Common Stock 2006-08-15 4 J 0 12518 A 12518 D Common Stock 2006-08-15 4 G 0 12518 A 0 D Distribution to partners. Represents shares beneficially held by Summit Ventures VI-A, L.P., Summit Ventures VI-B, L.P., Summit VI Advisors Fund, L.P., Summit VI Entrepreneurs Fund, L.P., Summit Subordinated Debt Fund II, L.P., and Summit Investors VI, L.P. Not applicable. Summit Partners, L.P. is the managing member of Summit Partners VI (GP), LLC, which is the general partner of Summit Partners VI (GP), L.P., which is the general partner of each of Summit Ventures VI-A, L.P., Summit Ventures VI-B, L.P., Summit VI Advisors Fund, L.P., Summit VI Entrepreneurs Fund, L.P. and Summit Investors VI, L.P. Summit Partners, L.P. is the managing member of Stamps, Woodsum & Co., IV, which is the general partner of Summit Partners SD II, LLC, which is the general part of Summit Subordinated Debt Fund II, L.P. Summit Partners, L.P. is the managing member of Summit Partners VI (GP), LLC, which is the general partner of Summit Partners VI (GP), L.P., which is the general partner of each of Summit Ventures VI-A, L.P., Summit Ventures VI-B, L.P., Summit VI Advisors Fund, L.P., Summit VI Entrepreneurs Fund, L.P. and Summit Investors VI, L.P. Summit Partners, L.P. is the managing member of Stamps, Woodsum & Co, IV, which is the general partner of Summit Partners SD II, LLC, which is the general partner of Summit Subordinated Debt Fund, L.P. Summit Partners, L.P. has voting and dispositive authority over the shares held by each of these entities and, therefore, may beneficially own such shares. Each of Summit Partners, L.P., Summit Partners VI (GP), LLC, Summit Partners VI (GP), L.P., Summit Partners SD II, LLC, and Summit Master Company, LLC, which is the general partner of Summit Partners, L.P., disclaims beneficial ownership of such shares, except to the extent of its pecuniary interest. Mr. Chung is a member of Summit Master Company, LLC, which is the general partner of Summit Partners, L.P. Mr. Chung disclaims beneficial ownership of such shares, except to the extent of his or its pecuniary interest therein. Robin W. Devereux, Power of Attorney for Peter Y. Chung 2006-08-15