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 0 100 18.65 A 5335197 I I Common Stock 2008-12-04 4 P 0 300 18.66 A 5335497 I I Common Stock 2008-12-04 4 P 0 200 18.67 A 5335697 I I Common Stock 2008-12-04 4 P 0 400 18.68 A 5336097 I I Common Stock 2008-12-04 4 P 0 400 18.72 A 5336497 I I Common Stock 2008-12-04 4 P 0 200 18.73 A 5336697 I I Common Stock 2008-12-04 4 P 0 200 18.74 A 5336897 I I Common Stock 2008-12-04 4 P 0 100 18.75 A 5336997 I I Common Stock 2008-12-04 4 P 0 200 18.76 A 5337197 I I Common Stock 2008-12-04 4 P 0 400 18.77 A 5337597 I I Common Stock 2008-12-04 4 P 0 400 18.79 A 5337997 I I Common Stock 2008-12-04 4 P 0 400 18.80 A 5338397 I I Common Stock 2008-12-04 4 P 0 200 18.82 A 5338597 I I Common Stock 2008-12-04 4 P 0 200 18.86 A 5338797 I I Common Stock 2008-12-04 4 P 0 400 18.89 A 5339197 I I Common Stock 2008-12-04 4 P 0 100 18.90 A 5339297 I I Common Stock 2008-12-04 4 P 0 100 18.94 A 5339397 I I Common Stock 2008-12-04 4 P 0 200 19.00 A 5339597 I I Common Stock 2008-12-04 4 P 0 200 19.04 A 5339797 I I Common Stock 2008-12-04 4 P 0 200 19.06 A 5339997 I I Common Stock 2008-12-04 4 P 0 200 19.08 A 5340197 I I Common Stock 2008-12-04 4 P 0 200 19.12 A 5340397 I I Common Stock 2008-12-04 4 P 0 600 19.14 A 5340997 I I Common Stock 2008-12-04 4 P 0 200 19.15 A 5341197 I I Common Stock 2008-12-04 4 P 0 400 19.18 A 5341597 I I Common Stock 2008-12-04 4 P 0 500 19.23 A 5342097 I I Common Stock 2008-12-04 4 P 0 300 19.29 A 5342397 I I Common Stock 2008-12-04 4 P 0 200 19.31 A 5342597 I I Common Stock 2008-12-04 4 P 0 200 19.32 A 5342797 I I Common Stock 2008-12-04 4 P 0 500 19.33 A 5343297 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