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 0 200 17.74 A 5304289 I I Common Stock 2008-12-04 4 P 0 100 17.75 A 5304389 I I Common Stock 2008-12-04 4 P 0 400 17.76 A 5304789 I I Common Stock 2008-12-04 4 P 0 1300 17.77 A 5306089 I I Common Stock 2008-12-04 4 P 0 1000 17.78 A 5307089 I I Common Stock 2008-12-04 4 P 0 300 17.79 A 5307389 I I Common Stock 2008-12-04 4 P 0 1000 17.80 A 5308389 I I Common Stock 2008-12-04 4 P 0 1400 17.81 A 5309789 I I Common Stock 2008-12-04 4 P 0 200 17.82 A 5309989 I I Common Stock 2008-12-04 4 P 0 1500 17.83 A 5311489 I I Common Stock 2008-12-04 4 P 0 200 17.84 A 5311689 I I Common Stock 2008-12-04 4 P 0 200 17.85 A 5311889 I I Common Stock 2008-12-04 4 P 0 200 17.86 A 5312089 I I Common Stock 2008-12-04 4 P 0 322 17.87 A 5312411 I I Common Stock 2008-12-04 4 P 0 100 17.88 A 5312511 I I Common Stock 2008-12-04 4 P 0 800 17.89 A 5313311 I I Common Stock 2008-12-04 4 P 0 800 17.90 A 5314111 I I Common Stock 2008-12-04 4 P 0 400 17.91 A 5314511 I I Common Stock 2008-12-04 4 P 0 978 17.92 A 5315489 I I Common Stock 2008-12-04 4 P 0 800 17.93 A 5316289 I I Common Stock 2008-12-04 4 P 0 400 17.95 A 5316689 I I Common Stock 2008-12-04 4 P 0 700 17.96 A 5317389 I I Common Stock 2008-12-04 4 P 0 700 17.98 A 5318089 I I Common Stock 2008-12-04 4 P 0 800 17.99 A 5318889 I I Common Stock 2008-12-04 4 P 0 200 18.00 A 5319089 I I Common Stock 2008-12-04 4 P 0 1500 18.01 A 5320589 I I Common Stock 2008-12-04 4 P 0 200 18.02 A 5320789 I I Common Stock 2008-12-04 4 P 0 300 18.03 A 5321089 I I Common Stock 2008-12-04 4 P 0 236 18.04 A 5321325 I I Common Stock 2008-12-04 4 P 0 200 18.05 A 5321525 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