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 16.98 A 5432711 I I Common Stock 2008-12-04 4 P 0 200 17.00 A 5432911 I I Common Stock 2008-12-04 4 P 0 400 17.01 A 5433311 I I Common Stock 2008-12-04 4 P 0 400 17.02 A 5433711 I I Common Stock 2008-12-04 4 P 0 600 17.03 A 5434311 I I Common Stock 2008-12-04 4 P 0 400 17.04 A 5434711 I I Common Stock 2008-12-04 4 P 0 200 17.05 A 5434911 I I Common Stock 2008-12-04 4 P 0 200 17.06 A 5435111 I I Common Stock 2008-12-04 4 P 0 400 17.07 A 5435511 I I Common Stock 2008-12-04 4 P 0 400 17.08 A 5435911 I I Common Stock 2008-12-04 4 P 0 600 17.10 A 5436511 I I Common Stock 2008-12-04 4 P 0 500 17.13 A 5437011 I I Common Stock 2008-12-04 4 P 0 200 17.16 A 5437211 I I Common Stock 2008-12-04 4 P 0 200 17.17 A 5437411 I I Common Stock 2008-12-04 4 P 0 200 17.20 A 5437611 I I Common Stock 2008-12-04 4 P 0 200 17.23 A 5437811 I I Common Stock 2008-12-04 4 P 0 700 17.24 A 5438511 I I Common Stock 2008-12-04 4 P 0 500 17.26 A 5439011 I I Common Stock 2008-12-04 4 P 0 1400 17.27 A 5440411 I I Common Stock 2008-12-04 4 P 0 200 17.30 A 5440611 I I Common Stock 2008-12-04 4 P 0 600 17.34 A 5441211 I I Common Stock 2008-12-04 4 P 0 200 17.35 A 5441411 I I Common Stock 2008-12-04 4 P 0 200 17.37 A 5441611 I I Common Stock 2008-12-04 4 P 0 200 17.38 A 5441811 I I Common Stock 2008-12-04 4 P 0 1000 17.40 A 5442811 I I Common Stock 2008-12-04 4 P 0 200 17.48 A 5443011 I I Common Stock 2008-12-04 4 P 0 200 17.51 A 5443211 I I Common Stock 2008-12-04 4 P 0 200 17.53 A 5443411 I I Common Stock 2008-12-04 4 P 0 400 17.55 A 5443811 I I Common Stock 2008-12-04 4 P 0 200 17.56 A 5444011 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