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 0 200 19.34 A 5343497 I I Common Stock 2008-12-04 4 P 0 400 19.35 A 5343897 I I Common Stock 2008-12-04 4 P 0 1000 19.37 A 5344897 I I Common Stock 2008-12-04 4 P 0 400 19.38 A 5345297 I I Common Stock 2008-12-04 4 P 0 400 19.39 A 5345697 I I Common Stock 2008-12-04 4 P 0 200 19.40 A 5345897 I I Common Stock 2008-12-04 4 P 0 200 19.41 A 5346097 I I Common Stock 2008-12-04 4 P 0 600 19.42 A 5346697 I I Common Stock 2008-12-04 4 P 0 600 19.43 A 5347297 I I Common Stock 2008-12-04 4 P 0 1200 19.44 A 5348497 I I Common Stock 2008-12-04 4 P 0 1945 19.45 A 5350442 I I Common Stock 2008-12-04 4 P 0 200 19.46 A 5350642 I I Common Stock 2008-12-04 4 P 0 900 19.47 A 5351542 I I Common Stock 2008-12-04 4 P 0 1600 19.48 A 5353142 I I Common Stock 2008-12-04 4 P 0 400 19.49 A 5353542 I I Common Stock 2008-12-04 4 P 0 4200 19.50 A 5357742 I I Common Stock 2008-12-04 4 P 0 100 17.83 A 5357842 I I Common Stock 2008-12-04 4 P 0 100 19.29 A 5357942 I I Common Stock 2008-12-04 4 P 0 200 19.36 A 5358142 I I Common Stock 2008-12-04 4 P 0 200 16.90 A 5358342 I I Common Stock 2008-12-04 4 P 0 200 16.93 A 5358542 I I Common Stock 2008-12-04 4 P 0 400 16.94 A 5358942 I I Common Stock 2008-12-04 4 P 0 100 16.95 A 5359042 I I Common Stock 2008-12-04 4 P 0 400 16.96 A 5359442 I I Common Stock 2008-12-04 4 P 0 200 16.97 A 5359642 I I Common Stock 2008-12-04 4 P 0 400 16.98 A 5360042 I I Common Stock 2008-12-04 4 P 0 500 16.99 A 5360542 I I Common Stock 2008-12-04 4 P 0 300 17.00 A 5360842 I I Common Stock 2008-12-04 4 P 0 800 17.02 A 5361642 I I Common Stock 2008-12-04 4 P 0 400 17.03 A 5362042 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