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 0 800 18.00 A 5393142 I I Common Stock 2008-12-04 4 P 0 900 18.01 A 5394042 I I Common Stock 2008-12-04 4 P 0 1000 18.02 A 5395042 I I Common Stock 2008-12-04 4 P 0 828 18.03 A 5395870 I I Common Stock 2008-12-04 4 P 0 200 18.04 A 5396070 I I Common Stock 2008-12-04 4 P 0 1200 18.05 A 5397270 I I Common Stock 2008-12-04 4 P 0 400 18.06 A 5397670 I I Common Stock 2008-12-04 4 P 0 300 18.07 A 5397970 I I Common Stock 2008-12-04 4 P 0 200 18.09 A 5398170 I I Common Stock 2008-12-04 4 P 0 200 18.11 A 5398370 I I Common Stock 2008-12-04 4 P 0 300 18.12 A 5398670 I I Common Stock 2008-12-04 4 P 0 400 18.13 A 5399070 I I Common Stock 2008-12-04 4 P 0 500 18.14 A 5399570 I I Common Stock 2008-12-04 4 P 0 200 18.15 A 5399770 I I Common Stock 2008-12-04 4 P 0 200 18.20 A 5399970 I I Common Stock 2008-12-04 4 P 0 800 18.23 A 5400770 I I Common Stock 2008-12-04 4 P 0 200 18.24 A 5400970 I I Common Stock 2008-12-04 4 P 0 700 18.25 A 5401670 I I Common Stock 2008-12-04 4 P 0 200 18.26 A 5401870 I I Common Stock 2008-12-04 4 P 0 200 18.27 A 5402070 I I Common Stock 2008-12-04 4 P 0 100 18.28 A 5402170 I I Common Stock 2008-12-04 4 P 0 400 18.29 A 5402570 I I Common Stock 2008-12-04 4 P 0 200 18.30 A 5402770 I I Common Stock 2008-12-04 4 P 0 200 18.31 A 5402970 I I Common Stock 2008-12-04 4 P 0 200 18.32 A 5403170 I I Common Stock 2008-12-04 4 P 0 400 18.33 A 5403570 I I Common Stock 2008-12-04 4 P 0 100 18.34 A 5403670 I I Common Stock 2008-12-04 4 P 0 400 18.35 A 5404070 I I Common Stock 2008-12-04 4 P 0 300 18.36 A 5404370 I I Common Stock 2008-12-04 4 P 0 300 18.37 A 5404670 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