X0306 4 2020-08-05 0 0001490892 CoreSite Realty Corp COR 0001548624 Carlyle Group Management L.L.C. C/O THE CARLYLE GROUP, 1001 PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH WASHINGTON DC 20004-2505 0 0 1 0 0001527166 Carlyle Group Inc. C/O THE CARLYLE GROUP, 1001 PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH WASHINGTON DC 20004-2505 0 0 1 0 0001548626 Carlyle Holdings I GP Inc. C/O THE CARLYLE GROUP, 1001 PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH WASHINGTON DC 20004-2505 0 0 1 0 0001548627 Carlyle Holdings I GP Sub L.L.C. C/O THE CARLYLE GROUP, 1001 PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH WASHINGTON DC 20004-2505 0 0 1 0 0001548628 Carlyle Holdings I L.P. C/O THE CARLYLE GROUP, 1001 PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH WASHINGTON DC 20004-2505 0 0 1 0 0001790577 CG Subsidiary Holdings L.L.C. C/O THE CARLYLE GROUP, 1001 PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH WASHINGTON DC 20004-2505 0 0 1 0 0000933790 TC Group, LLC C/O THE CARLYLE GROUP, 1001 PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH WASHINGTON DC 20004-2505 0 0 1 0 0001548639 TC Group Sub L.P. C/O THE CARLYLE GROUP, 1001 PENNSYLVANIA AVE., N.W. SUITE 220 SOUTH WASHINGTON DC 20004-2505 0 0 1 0 Common Stock 2020-08-05 4 M 0 230172 A 230172 I See footnotes Common Stock 2020-08-05 4 S 0 230172 128.55 D 0 I See footnotes Operating Partnership Units 2020-08-05 4 M 0 230172 D Common Stock 230172 5875218 I See footnotes The operating partnership units are redeemable at any time for cash or, at the election of the Issuer, exchangeable for shares of common stock on a one-for-one basis, and have no expiration date. Following the transaction reported herein, the common units are held by CoreSite CRP V Holdings, LLC. Following an internal reorganization and by reason of the relationships described below, the reporting person may be deemed to share beneficial ownership of the securities reported herein. Each reporting person disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. Carlyle Group Management L.L.C. holds an irrevocable proxy to vote a majority of the shares of The Carlyle Group Inc., which is a publicly traded entity listed on NASDAQ. The Carlyle Group Inc. is the sole shareholder of Carlyle Holdings I GP Inc., which is the sole member of Carlyle Holdings I GP Sub L.L.C., which is the general partner of Carlyle Holdings I L.P., which, with respect to the securities reported herein, is the managing member of CG Subsidiary Holdings L.L.C., which is the managing member of TC Group, L.L.C., which is the general partner of TC Group Sub L.P., which is the sole member of Carlyle Realty V GP, L.L.C., which is the general partner of Carlyle Realty V, L.P., which is the manager of CoreSite CRP V Holdings, LLC Due to the limitations of the electronic filing system Carlyle Realty V GP, L.L.C., Carlyle Realty V, L.P. and CoreSite CRP V Holdings, LLC are filing a separate Form 4. Carlyle Group Management L.L.C, By: /s/ Anne Frederick, Attorney-in-fact for Curtis L. Buser, Chief Financial Officer 2020-08-07 The Carlyle Group Inc., By: /s/ Anne Frederick, Attorney-in-fact for Curtis L. Buser, Chief Financial Officer 2020-08-07 Carlyle Holdings I GP Inc., By: /s/ Anne Frederick, Attorney-in-fact for Curtis L. Buser, Chief Financial Officer 2020-08-07 Carlyle Holdings I GP Sub L.L.C., By: Carlyle Holdings I GP Inc., its sole member, By: /s/ Anne Frederick, Attorney-in-fact for Curtis L. Buser, Chief Financial Officer 2020-08-07 Carlyle Holdings I L.P., By: /s/ Anne Frederick, Attorney-in-fact for Curtis L. Buser, Chief Financial Officer 2020-08-07 CG Subsidiary Holdings L.L.C., By: Carlyle Holdings I L.P., its managing member, By: /s/ Anne Frederick, Attorney-in-fact for Curtis L. Buser, Chief Financial Officer 2020-08-07 TC Group, L.L.C., By: CG Subsidiary Holdings L.L.C.., its managing member, By: Carlyle Holdings I L.P., its managing member, By: /s/ Anne Frederick, Attorney-in-fact for Curtis L. Buser, Chief Financial Officer 2020-08-07 TC Group Sub L.P., By: TC Group, L.L.C., its general partner, By: CG Subsidiary Holdings L.L.C., its managing member, By: Carlyle Holdings I L.P., its managing member, By: /s/ Anne Frederick, Attorney-in-fact for Curtis L. Buser, Chief Financial Officer 2020-08-07