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 19.76 A 5252390 I I Common Stock 2008-12-03 4 P 0 400 19.77 A 5252790 I I Common Stock 2008-12-03 4 P 0 2000 19.78 A 5254790 I I Common Stock 2008-12-03 4 P 0 3342 19.79 A 5258132 I I Common Stock 2008-12-03 4 P 0 2000 19.80 A 5260132 I I Common Stock 2008-12-03 4 P 0 6400 19.81 A 5266532 I I Common Stock 2008-12-03 4 P 0 6058 19.82 A 5272590 I I Common Stock 2008-12-03 4 P 0 2098 19.83 A 5274688 I I Common Stock 2008-12-03 4 P 0 400 19.84 A 5275088 I I Common Stock 2008-12-03 4 P 0 200 19.85 A 5275288 I I Common Stock 2008-12-03 4 P 0 300 19.86 A 5275588 I I Common Stock 2008-12-03 4 P 0 200 19.87 A 5275788 I I Common Stock 2008-12-03 4 P 0 1800 19.88 A 5277588 I I Common Stock 2008-12-03 4 P 0 200 19.90 A 5277788 I I Common Stock 2008-12-03 4 P 0 200 19.91 A 5277988 I I Common Stock 2008-12-03 4 P 0 2600 19.92 A 5280588 I I Common Stock 2008-12-03 4 P 0 400 19.93 A 5280988 I I Common Stock 2008-12-03 4 P 0 1900 19.94 A 5282888 I I Common Stock 2008-12-03 4 P 0 4400 19.95 A 5287288 I I Common Stock 2008-12-03 4 P 0 600 19.96 A 5287888 I I Common Stock 2008-12-03 4 P 0 1400 19.98 A 5289288 I I Common Stock 2008-12-03 4 P 0 1800 19.99 A 5291088 I I Common Stock 2008-12-04 4 P 0 200 16.90 A 5291288 I I Common Stock 2008-12-04 4 P 0 300 16.94 A 5291588 I I Common Stock 2008-12-04 4 P 0 501 16.96 A 5292089 I I Common Stock 2008-12-04 4 P 0 200 16.98 A 5292289 I I Common Stock 2008-12-04 4 P 0 600 16.99 A 5292889 I I Common Stock 2008-12-04 4 P 0 300 17.00 A 5293189 I I Common Stock 2008-12-04 4 P 0 100 17.01 A 5293289 I I Common Stock 2008-12-04 4 P 0 200 17.02 A 5293489 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