X0303 4 2008-12-03 0 0001172139 BILL BARRETT CORP BBG 0000929408 WARBURG PINCUS & CO C/O WARBURG PINCUS LLC 466 LEXINGTON AVENUE, 10TH FLOOR NEW YORK NY 10017 0 0 1 0 0001414565 Warburg Pincus Private Equity X, L.P. C/O WARBURG PINCUS LLC 466 LEXINGTON AVENUE, 10TH FLOOR NEW YORK NY 10017 0 0 1 0 0001414561 Warburg Pincus X, L.P. C/O WARBURG PINCUS LLC 466 LEXINGTON AVENUE, 10TH FLOOR NEW YORK NY 10017 0 0 1 0 0001414564 Warburg Pincus X LLC C/O WARBURG PINCUS LLC 466 LEXINGTON AVENUE, 10TH FLOOR NEW YORK NY 10017 0 0 1 0 0001157334 WARBURG PINCUS PRIVATE EQUITY VIII L P C/O WARBURG PINCUS LLC 466 LEXINGTON AVENUE, 10TH FLOOR NEW YORK NY 10017 0 0 1 0 0001322709 Warburg Pincus Partners LLC C/O WARBURG PINCUS LLC 466 LEXINGTON AVENUE, 10TH FLOOR NEW YORK NY 10017 0 0 1 0 0001162870 WARBURG PINCUS LLC C/O WARBURG PINCUS LLC 466 LEXINGTON AVENUE, 10TH FLOOR NEW YORK NY 10017 0 0 1 0 Common Stock 2008-12-04 4 P 0 300 18.06 A 5321825 I I Common Stock 2008-12-04 4 P 0 400 18.07 A 5322225 I I Common Stock 2008-12-04 4 P 0 200 18.10 A 5322425 I I Common Stock 2008-12-04 4 P 0 1272 18.17 A 5323697 I I Common Stock 2008-12-04 4 P 0 200 18.18 A 5323897 I I Common Stock 2008-12-04 4 P 0 200 18.19 A 5324097 I I Common Stock 2008-12-04 4 P 0 100 18.24 A 5324197 I I Common Stock 2008-12-04 4 P 0 300 18.25 A 5324497 I I Common Stock 2008-12-04 4 P 0 400 18.26 A 5324897 I I Common Stock 2008-12-04 4 P 0 600 18.27 A 5325497 I I Common Stock 2008-12-04 4 P 0 1300 18.28 A 5326797 I I Common Stock 2008-12-04 4 P 0 300 18.29 A 5327097 I I Common Stock 2008-12-04 4 P 0 200 18.30 A 5327297 I I Common Stock 2008-12-04 4 P 0 600 18.31 A 5327897 I I Common Stock 2008-12-04 4 P 0 400 18.32 A 5328297 I I Common Stock 2008-12-04 4 P 0 400 18.33 A 5328697 I I Common Stock 2008-12-04 4 P 0 400 18.34 A 5329097 I I Common Stock 2008-12-04 4 P 0 400 18.36 A 5329497 I I Common Stock 2008-12-04 4 P 0 100 18.37 A 5329597 I I Common Stock 2008-12-04 4 P 0 300 18.39 A 5329897 I I Common Stock 2008-12-04 4 P 0 100 18.42 A 5329997 I I Common Stock 2008-12-04 4 P 0 400 18.43 A 5330397 I I Common Stock 2008-12-04 4 P 0 200 18.44 A 5330597 I I Common Stock 2008-12-04 4 P 0 400 18.47 A 5330997 I I Common Stock 2008-12-04 4 P 0 200 18.48 A 5331197 I I Common Stock 2008-12-04 4 P 0 1000 18.49 A 5332197 I I Common Stock 2008-12-04 4 P 0 1300 18.50 A 5333497 I I Common Stock 2008-12-04 4 P 0 800 18.51 A 5334297 I I Common Stock 2008-12-04 4 P 0 600 18.52 A 5334897 I I Common Stock 2008-12-04 4 P 0 200 18.54 A 5335097 I I See Exhibit 99.1 See Exhibit 99.1 Exhibit List: Exhibit 99.1 - Explanation of Responses Exhibit 99.2 - Joint Filers' Names and Addresses Exhibit 99.3 - Joint Filers' Signatures WARBURG PINCUS & CO. By: /s/ Name: Scott A. Arenare, Title: Partner 2008-12-05