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 2008-12-03 4 P 0 1700 19.15 A 5127286 I I Common Stock 2008-12-03 4 P 0 2100 19.16 A 5129386 I I Common Stock 2008-12-03 4 P 0 400 19.17 A 5129786 I I Common Stock 2008-12-03 4 P 0 2500 19.18 A 5132286 I I Common Stock 2008-12-03 4 P 0 900 19.19 A 5133186 I I Common Stock 2008-12-03 4 P 0 200 19.20 A 5133386 I I Common Stock 2008-12-03 4 P 0 900 19.21 A 5134286 I I Common Stock 2008-12-03 4 P 0 1200 19.22 A 5135486 I I Common Stock 2008-12-03 4 P 0 5918 19.23 A 5141404 I I Common Stock 2008-12-03 4 P 0 4400 19.24 A 5145804 I I Common Stock 2008-12-03 4 P 0 5482 19.25 A 5151286 I I Common Stock 2008-12-03 4 P 0 1600 19.26 A 5152886 I I Common Stock 2008-12-03 4 P 0 2600 19.27 A 5155486 I I Common Stock 2008-12-03 4 P 0 3000 19.28 A 5158486 I I Common Stock 2008-12-03 4 P 0 1400 19.29 A 5159886 I I Common Stock 2008-12-03 4 P 0 6100 19.30 A 5165986 I I Common Stock 2008-12-03 4 P 0 4200 19.31 A 5170186 I I Common Stock 2008-12-03 4 P 0 1200 19.32 A 5171386 I I Common Stock 2008-12-03 4 P 0 4102 19.33 A 5175488 I I Common Stock 2008-12-03 4 P 0 3000 19.34 A 5178488 I I Common Stock 2008-12-03 4 P 0 1200 19.35 A 5179688 I I Common Stock 2008-12-03 4 P 0 900 19.36 A 5180588 I I Common Stock 2008-12-03 4 P 0 1600 19.37 A 5182188 I I Common Stock 2008-12-03 4 P 0 2200 19.38 A 5184388 I I Common Stock 2008-12-03 4 P 0 2400 19.39 A 5186788 I I Common Stock 2008-12-03 4 P 0 3000 19.40 A 5189788 I I Common Stock 2008-12-03 4 P 0 1200 19.41 A 5190988 I I Common Stock 2008-12-03 4 P 0 2000 19.42 A 5192988 I I Common Stock 2008-12-03 4 P 0 3300 19.43 A 5196288 I I Common Stock 2008-12-03 4 P 0 4800 19.44 A 5201088 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