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 0 400 18.79 A 5486675 I I Common Stock 2008-12-04 4 P 0 200 18.80 A 5486875 I I Common Stock 2008-12-04 4 P 0 200 18.82 A 5487075 I I Common Stock 2008-12-04 4 P 0 200 18.86 A 5487275 I I Common Stock 2008-12-04 4 P 0 200 18.90 A 5487475 I I Common Stock 2008-12-04 4 P 0 600 18.98 A 5488075 I I Common Stock 2008-12-04 4 P 0 700 18.99 A 5488775 I I Common Stock 2008-12-04 4 P 0 200 19.00 A 5488975 I I Common Stock 2008-12-04 4 P 0 400 19.01 A 5489375 I I Common Stock 2008-12-04 4 P 0 800 19.02 A 5490175 I I Common Stock 2008-12-04 4 P 0 200 19.04 A 5490375 I I Common Stock 2008-12-04 4 P 0 200 19.16 A 5490575 I I Common Stock 2008-12-04 4 P 0 200 19.17 A 5490775 I I Common Stock 2008-12-04 4 P 0 800 19.19 A 5491575 I I Common Stock 2008-12-04 4 P 0 600 19.20 A 5492175 I I Common Stock 2008-12-04 4 P 0 800 19.21 A 5492975 I I Common Stock 2008-12-04 4 P 0 200 19.23 A 5493175 I I Common Stock 2008-12-04 4 P 0 600 19.24 A 5493775 I I Common Stock 2008-12-04 4 P 0 100 19.25 A 5493875 I I Common Stock 2008-12-04 4 P 0 500 19.29 A 5494375 I I Common Stock 2008-12-04 4 P 0 400 19.31 A 5494775 I I Common Stock 2008-12-04 4 P 0 200 19.32 A 5494975 I I Common Stock 2008-12-04 4 P 0 313 19.33 A 5495288 I I Common Stock 2008-12-04 4 P 0 200 19.34 A 5495488 I I Common Stock 2008-12-04 4 P 0 400 19.35 A 5495888 I I Common Stock 2008-12-04 4 P 0 600 19.36 A 5496488 I I Common Stock 2008-12-04 4 P 0 400 19.38 A 5496888 I I Common Stock 2008-12-04 4 P 0 600 19.40 A 5497488 I I Common Stock 2008-12-04 4 P 0 600 19.41 A 5498088 I I Common Stock 2008-12-04 4 P 0 800 19.42 A 5498888 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