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 0 200 19.45 A 5201288 I I Common Stock 2008-12-03 4 P 0 7200 19.45 A 5208488 I I Common Stock 2008-12-03 4 P 0 5900 19.46 A 5214388 I I Common Stock 2008-12-03 4 P 0 2300 19.47 A 5216688 I I Common Stock 2008-12-03 4 P 0 2700 19.48 A 5219388 I I Common Stock 2008-12-03 4 P 0 900 19.49 A 5220288 I I Common Stock 2008-12-03 4 P 0 1200 19.50 A 5221488 I I Common Stock 2008-12-03 4 P 0 3200 19.51 A 5224688 I I Common Stock 2008-12-03 4 P 0 1200 19.52 A 5225888 I I Common Stock 2008-12-03 4 P 0 800 19.53 A 5226688 I I Common Stock 2008-12-03 4 P 0 600 19.54 A 5227288 I I Common Stock 2008-12-03 4 P 0 1400 19.55 A 5228688 I I Common Stock 2008-12-03 4 P 0 2 19.56 A 5228690 I I Common Stock 2008-12-03 4 P 0 800 19.58 A 5229490 I I Common Stock 2008-12-03 4 P 0 2000 19.59 A 5231490 I I Common Stock 2008-12-03 4 P 0 4300 19.60 A 5235790 I I Common Stock 2008-12-03 4 P 0 100 19.61 A 5235890 I I Common Stock 2008-12-03 4 P 0 100 19.62 A 5235990 I I Common Stock 2008-12-03 4 P 0 800 19.63 A 5236790 I I Common Stock 2008-12-03 4 P 0 400 19.64 A 5237190 I I Common Stock 2008-12-03 4 P 0 1400 19.66 A 5238590 I I Common Stock 2008-12-03 4 P 0 200 19.67 A 5238790 I I Common Stock 2008-12-03 4 P 0 1200 19.68 A 5239990 I I Common Stock 2008-12-03 4 P 0 800 19.69 A 5240790 I I Common Stock 2008-12-03 4 P 0 600 19.70 A 5241390 I I Common Stock 2008-12-03 4 P 0 1800 19.71 A 5243190 I I Common Stock 2008-12-03 4 P 0 2000 19.72 A 5245190 I I Common Stock 2008-12-03 4 P 0 600 19.73 A 5245790 I I Common Stock 2008-12-03 4 P 0 800 19.74 A 5246590 I I Common Stock 2008-12-03 4 P 0 5600 19.75 A 5252190 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