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 0 600 19.05 A 5417770 I I Common Stock 2008-12-04 4 P 0 1000 19.06 A 5418770 I I Common Stock 2008-12-04 4 P 0 200 19.11 A 5418970 I I Common Stock 2008-12-04 4 P 0 255 19.12 A 5419225 I I Common Stock 2008-12-04 4 P 0 1500 19.18 A 5420725 I I Common Stock 2008-12-04 4 P 0 400 19.20 A 5421125 I I Common Stock 2008-12-04 4 P 0 800 19.21 A 5421925 I I Common Stock 2008-12-04 4 P 0 400 19.26 A 5422325 I I Common Stock 2008-12-04 4 P 0 600 19.28 A 5422925 I I Common Stock 2008-12-04 4 P 0 200 19.29 A 5423125 I I Common Stock 2008-12-04 4 P 0 200 19.30 A 5423325 I I Common Stock 2008-12-04 4 P 0 400 19.31 A 5423725 I I Common Stock 2008-12-04 4 P 0 400 19.34 A 5424125 I I Common Stock 2008-12-04 4 P 0 400 19.35 A 5424525 I I Common Stock 2008-12-04 4 P 0 1000 19.36 A 5425525 I I Common Stock 2008-12-04 4 P 0 400 19.38 A 5425925 I I Common Stock 2008-12-04 4 P 0 200 19.39 A 5426125 I I Common Stock 2008-12-04 4 P 0 200 19.41 A 5426325 I I Common Stock 2008-12-04 4 P 0 400 19.42 A 5426725 I I Common Stock 2008-12-04 4 P 0 500 19.43 A 5427225 I I Common Stock 2008-12-04 4 P 0 200 19.44 A 5427425 I I Common Stock 2008-12-04 4 P 0 600 19.45 A 5428025 I I Common Stock 2008-12-04 4 P 0 1000 19.46 A 5429025 I I Common Stock 2008-12-04 4 P 0 400 19.47 A 5429425 I I Common Stock 2008-12-04 4 P 0 800 19.48 A 5430225 I I Common Stock 2008-12-04 4 P 0 1000 19.49 A 5431225 I I Common Stock 2008-12-04 4 P 0 787 19.50 A 5432012 I I Common Stock 2008-12-04 4 P 0 99 16.93 A 5432111 I I Common Stock 2008-12-04 4 P 0 200 16.95 A 5432311 I I Common Stock 2008-12-04 4 P 0 200 16.96 A 5432511 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