X0306 4 2021-03-03 0 0000883902 Cornerstone Building Brands, Inc. CNR 0001492387 GGC Opportunity Fund Management GP, Ltd. C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 0001759041 ATRIUM INTERMEDIATE HOLDINGS, LLC C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER, 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 0001759048 ATRIUM WINDOW HOLDINGS, LLC C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER, 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 0001759064 ATRIUM WINDOW PARENT, LLC C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER, 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 0001759054 GGC ATRIUM WINDOW HOLDINGS, LLC C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER, 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 0001759082 GGC BP HOLDINGS, LLC C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER, 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 0001437622 GOLDEN GATE CAPITAL OPPORTUNITY FUND, L.P. C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER, 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 0001411087 GOLDEN GATE CAPITAL OPPORTUNITY FUND-A, L.P. C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER, 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 0001492388 GGCOF Co-Invest Management, L.P. C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER, 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 0001431072 GGCOF CO-INVEST, L.P. C/O GOLDEN GATE PRIVATE EQUITY, INC. ONE EMBARCADERO CENTER, 39TH FLOOR SAN FRANCISCO CA 94111 0 0 1 0 Common Stock, $0.01 par value 2021-03-03 4 S 0 150000 11.62 D 1404586 I See notes Common Stock, $0.01 par value 2021-03-04 4 S 0 277800 12.31 D 1126786 I See notes Common Stock, $0.01 par value 2021-03-05 4 S 0 385000 12.52 D 741786 I See notes Common Stock, $0.01 par value 12441252.4 I See note Common Stock, $0.01 par value 48150.31 I See note Weighted average price representing high of $11.78 and low of $11.50. Shares are directly held by AIC Finance Partnership, L.P. ("AIC"). Each of Golden Gate Capital Opportunity Fund, L.P. ("GGCOF"), Golden Gate Capital Opportunity Fund-A, L.P. ("GGCOF-A"), GGCOF Co-Invest, L.P. ("GGCOF Co-Invest"), GGCOF Co-Invest IRA, L.P. ("IRA Co-Invest") and GGCOF Executive Co-Invest, L.P. ("Executive Co-Invest" and, together with GGCOF, GGCOF-A, GGCOF Co-Invest and IRA Co-Invest, the "Funds") have an indirect pecuniary interest in AIC. GGCOF Co-Invest Management, L.P. ("GGCOF Third Party Co-Invest") is the general partner of each of GGCOF Co-Invest, IRA Co-Invest and Executive Co-Invest. GGC Opportunity Fund Management, L.P. ("Management GP") is the general partner of each of GGCOF, GGCOF-A and GGCOF Third Party Co-Invest, and GGC Opportunity Fund Management GP, Ltd. (Continued from Footnote 3) ("Ultimate GP") is the general partner of Management GP. Ultimate GP is governed by its board of directors. Each of the Funds, GGCOF Third Party Co-Invest, Management GP and Ultimate GP disclaim beneficial ownership of these shares except to the extent of their respective pecuniary interests therein. Weighted average price representing high of $12.78 and low of $11.80. Weighted average price representing high of $12.82 and low of $12.15. Shares are directly held by Atrium Intermediate Holdings, LLC ("Atrium Intermediate"). Atrium Window Holdings, LLC ("Atrium Holdings") and Atrium Window Parent, LLC ("Atrium Parent") are the members of Atrium Intermediate. Atrium Parent is the controlling unitholder of Atrium Holdings. GGC Atrium Window Holdings, LLC ("GGC Atrium') is the controlling unitholder of Atrium Parent. GGC BP Holdings, LLC ("GGC BP") is the controlling unitholder of GGC Atrium. The Funds collectively hold all of the equity interests of GGC BP. Each of Funds, GGCOF Third Party Co-Invest, Management GP and Ultimate GP disclaim beneficial ownership of these shares except to the extent of their respective pecuniary interests therein. Shares are directly held by GGC BP. Each of the Funds, GGCOF Third Party Co-Invest, Management GP and Ultimate GP disclaim beneficial ownership of these shares except to the extent of their respective pecuniary interests therein. Form 1 of 2 GGC Opportunity Fund Management GP, Ltd., By: /s/ Stephen D. Oetgen, attorney-in-fact for David Dominik, a Director 2021-03-05 Golden Gate Capital Opportunity Fund, L.P., By: /s/ Stephen D. Oetgen, attorney-in-fact for David Dominik, a Director 2021-03-05 Golden Gate Capital Opportunity Fund-A, L.P., By: /s/ Stephen D. Oetgen, attorney-in-fact for David Dominik, a Director 2021-03-05 GGCOF Co-Invest Management, L.P., By: /s/ Stephen D. Oetgen, attorney-in-fact for David Dominik, a Director 2021-03-05 GGCOF Co-Invest, L.P., By: /s/ Stephen D. Oetgen, attorney-in-fact for David Dominik, a Director 2021-03-05 Atrium Intermediate Holdings, LLC, By: /s/ Stephen D. Oetgen, attorney-in-fact for David Thomas, a Manager 2021-03-05 Atrium Window Holdings, LLC, By: /s/ Stephen D. Oetgen, attorney-in-fact for David Thomas, a Manager 2021-03-05 Atrium Window Parent, LLC, By: /s/ Stephen D. Oetgen, attorney-in-fact for David Thomas, a Manager 2021-03-05 GGC Atrium Window Holdings, LLC, By: /s/ Stephen D. Oetgen, attorney-in-fact for David Thomas, a Manager 2021-03-05 GGC BP Holdings, LLC, By: /s/ Stephen D. Oetgen, attorney-in-fact for David Thomas, a Manager 2021-03-05