X0306 4 2018-08-07 0 0000007431 ARMSTRONG WORLD INDUSTRIES INC AWI 0001418814 ValueAct Holdings, L.P. ONE LETTERMAN DRIVE BUILDING D, 4TH FLOOR SAN FRANCISCO CA 94129 1 0 1 1 See Remarks 0001464912 ValueAct Capital Master Fund, L.P. ONE LETTERMAN DRIVE BUILDING D, 4TH FLOOR SAN FRANCISCO CA 94129 1 0 1 1 See Remarks 0001418812 VA Partners I, LLC ONE LETTERMAN DRIVE BUILDING D, 4TH FLOOR SAN FRANCISCO CA 94129 1 0 1 1 See Remarks 0001351069 ValueAct Capital Management, L.P. ONE LETTERMAN DRIVE BUILDING D, 4TH FLOOR SAN FRANCISCO CA 94129 1 0 1 1 See Remarks 0001351073 ValueAct Capital Management, LLC ONE LETTERMAN DRIVE BUILDING D, 4TH FLOOR SAN FRANCISCO CA 94129 1 0 1 1 See Remarks 0001418813 ValueAct Holdings GP, LLC ONE LETTERMAN DRIVE BUILDING D, 4TH FLOOR SAN FRANCISCO CA 94129 1 0 1 1 See Remarks Common Stock 2018-08-07 4 S 0 1500000 69.2 D 5354910 I See Footnotes Each reporting person listed herein disclaims beneficial ownership of the reported securities except to the extent of its pecuniary interest therein, and this report shall not be deemed an admission that such person is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose. The securities reported herein are directly beneficially owned by ValueAct Capital Master Fund, L.P. and may be deemed to be indirectly beneficially owned by (i) VA Partners I, LLC as General Partner of ValueAct Capital Master Fund, L.P. , (ii) ValueAct Capital Management, L.P. as the manager of ValueAct Capital Master Fund, L.P. , (iii) ValueAct Capital Management, LLC as General Partner of ValueAct Capital Management, L.P., (iv) ValueAct Holdings, L.P. as the sole owner of the limited partnership interests of ValueAct Capital Management, L.P. and the membership interests of ValueAct Capital Management, LLC and as the majority owner of the membership interests of VA Partners I, LLC and (v) ValueAct Holdings GP, LLC as General Partner of ValueAct Holdings, L.P. - The reporting persons herein may be deemed to be members of a "group" for purposes of the Securities Exchange Act of 1934, as amended. Each reporting person disclaims beneficial ownership of any securities deemed to be owned by the group that are not directly owned by such reporting person. This report shall not be deemed an admission that such reporting person is a member of a group or the beneficial owner of any securities not directly owned by such reporting person. - Gregory P. Spivy, a Partner at ValueAct Capital, serves on the board of directors of the Issuer. As a result, the other reporting persons herein may be deemed directors by deputization. VALUEACT HOLDINGS, L.P., By: VALUEACT HOLDINGS GP, LLC, its General Partner, By: /s/ Bradley E. Singer, Chief Operating Officer 2018-08-09 VALUEACT CAPITAL MASTER FUND, L.P., By: VA PARTNERS I, LLC, its General Partner, By: /s/ Bradley E. Singer, Chief Operating Officer 2018-08-09 VA PARTNERS I, LLC, By: /s/ Bradley E. Singer, Chief Operating Officer 2018-08-09 VALUEACT CAPITAL MANAGEMENT, L.P., By: VALUEACT CAPITAL MANAGEMENT, LLC, its General Partner, By: /s/ Bradley E. Singer, Chief Operating Officer 2018-08-09 VALUEACT CAPITAL MANAGEMENT, LLC, By: /s/ Bradley E. Singer, Chief Operating Officer 2018-08-09 VALUEACT HOLDINGS GP, LLC, By: /s/ Bradley E. Singer, Chief Operating Officer 2018-08-09