Agreement and Plan of Merger by and among American Tower Investments Llc, Appleseed Holdco Llc, Appleseed Merger Sub Llc, Appleseed Op Merger Sub Llc, Coresite Realty Corporation, Coresite, L.p. And Solely for Purposes of ​section 2.4(c), ​section 2.4(e), ​section 4.1, ​section 4.2, ​ Section 4.4, ​section 4.5(a)(ii), ​section 4.5(c), ​section 4.5(d), ​section 4.5(e), ​section 4.9, ​section 4.12, ​section 6.3, ​section 6.13, ​section 6.14 and ​article Ix, American Tower Corporation

• Date: 14 November 2021
• Section: Merger Agreements

AGREEMENT AND PLAN OF MERGER by and among AMERICAN TOWER INVESTMENTS LLC,

APPLESEED HOLDCO LLC, APPLESEED MERGER SUB LLC, APPLESEED OP MERGER SUB LLC,

CORESITE REALTY CORPORATION, CORESITE, L.P. and SOLELY FOR PURPOSES OF

Section 2.4(c), Section 2.4(e), Section 4.1, Section 4.2, Section 4.4, Section

4.5(a)(ii), Section 4.5(c), Section 4.5(d), Section 4.5(e), Section 4.9, Section

4.12, Section 6.3, Section 6.13, Section 6.14 and Article IX, AMERICAN TOWER

CORPORATION dated as of November 14, 2021

TABLE OF CONTENTS Page ARTICLE I THE TRANSACTIONS 3 Section 1.1

The Offer 3 Section 1.2 Additional Actions 6 Section 1.3 Stockholder Lists 8

Section 1.4 The Partnership Merger 8 Section 1.5 The Company Merger 8 Section

1.6 The Holdco Merger 8 Section 1.7 Closing 9 Section 1.8 Effective Time 9

Section 1.9 Governing Documents 10 Section 1.10 Officers and Directors of the

Surviving Entities 10 Section 1.11 Tax Consequences 11 ARTICLE II TREATMENT

OF SECURITIES 11 Section 2.1 Treatment of Capital Stock 11 Section 2.2

Payment for Securities; Surrender of Certificates 13 Section 2.3 Dissenter’s

Rights 15 Section 2.4 Treatment of Company Equity Awards 15 Section 2.5

Withholding 17 ARTICLE III REPRESENTATIONS AND WARRANTIES OF THE COMPANY

AND COMPANY OPERATING PARTNERSHIP 17 Section 3.1 Qualification,

Organization, Subsidiaries 17 Section 3.2 Capitalization 18 Section 3.3

Authorization; Validity of Agreement; Necessary Action 19 Section 3.4 Corporate

Approvals 20 Section 3.5 Consents and Approvals; No Violations 21 Section 3.6

Company SEC Documents and Financial Statements 21 Section 3.7 Internal Controls

and Procedures 22

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Section 3.8 Absence of Certain Changes 23 Section 3.9 No Undisclosed Liabilities

23 Section 3.10 Litigation 23 Section 3.11 Company Benefit Plans 23 Section 3.12

Labor Matters 26 Section 3.13 Taxes 26 Section 3.14 Company Material Contracts

29 Section 3.15 Environmental Matters 31 Section 3.16 Intellectual Property 31

Section 3.17 Privacy; Cybersecurity; IT Assets 32 Section 3.18 Compliance with

Laws; Permits 33

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Section 3.19 Properties 35 Section 3.20 Information in the Offer Documents 36

Section 3.21 Opinion of Company Financial Advisor 36 Section 3.22 Insurance 36

Section 3.23 Related Party Agreements 36 Section 3.24 Brokers; Expenses 37

Section 3.25 Takeover Statutes 37 Section 3.26 Dissenters’ Rights 37 Section

3.27 Vote Required 37 Section 3.28 Investment Company Act 37 Section 3.29

Investigation; Limitation on Warranties; Disclaimer of Other Representations and

Warranties 37 Section 3.30 No Other Representations or Warranties 38

ARTICLE IV REPRESENTATIONS AND WARRANTIES OF THE PARENT PARTIES 38 Section

4.1 Qualification, Organization, Subsidiaries 38 Section 4.2 Authorization;

Validity of Agreement; Necessary Action 39 Section 4.3 Corporate Approvals 39

Section 4.4 Consents and Approvals; No Violations 39 Section 4.5 Taxes 40

Section 4.6 Information in the Offer Documents 41 Section 4.7 Ownership of

Company Common Stock 42 Section 4.8 Brokers and Other Advisors 42 Section 4.9

Vote Required 42 Section 4.10 Financing 42 Section 4.11 Operations of Holdco,

Purchaser and OP Merger Sub 43 Section 4.12 Investigation; Limitation on

Warranties; Disclaimer of Other Representations and Warranties 43 Section 4.13

No Other Representations or Warranties 44 ARTICLE V CONDUCT OF BUSINESS

PENDING THE MERGERS 44 Section 5.1 Conduct of Business by the Company

Pending the Closing 44 Section 5.2 No Solicitation; Company Change in

Recommendation 49 ARTICLE VI ADDITIONAL AGREEMENTS 53 Section 6.1

Access; Confidentiality 53 Section 6.2 Consents and Approvals 54 Section 6.3

Publicity 56 Section 6.4 Directors’ and Officers’ Insurance and Indemnification

56 Section 6.5 Employee Matters 58 Section 6.6 Takeover Statutes 60 Section 6.7

Rule 16b-3 60 Section 6.8 COVID-19 60

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Section 6.9 Stockholder Litigation 60 Section 6.10 Director Resignations 61

Section 6.11 Tax Matters 61 Section 6.12 Dividends 61 Section 6.13 Parent

Guarantor Financing Covenant 62 Section 6.14 Financing Cooperation 63 Section

6.15 Existing Company Indebtedness 66 Section 6.16 Notification of Certain

Matters 68 ARTICLE VII CONDITIONS TO CONSUMMATION OF THE MERGERS 69

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Section 7.1 Conditions to Each Party’s Obligations to Effect the Mergers 69

ARTICLE VIII TERMINATION 69 Section 8.1 Termination 69 Section 8.2 Effect

of Termination 71 ARTICLE IX MISCELLANEOUS 73 Section 9.1 Amendment

and Modification; Waiver 73 Section 9.2 Non-Survival of Representations and

Warranties 74 Section 9.3 Expenses 74 Section 9.4 Notices 74 Section 9.5 Certain

Definitions 75 Section 9.6 Terms Defined Elsewhere 86 Section 9.7 Interpretation

88 Section 9.8 Counterparts; Effectiveness 89 Section 9.9 Entire Agreement;

Third-Party Beneficiaries 89 Section 9.10 Severability 89 Section 9.11 Governing

Law; Jurisdiction 90 Section 9.12 Waiver of Jury Trial 91 Section 9.13

Assignment 91 Section 9.14 Specific Enforcement 91 Section 9.15 Non-Recourse 92

Section 9.16 Guaranty 92 Annex I Offer Conditions

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AGREEMENT AND PLAN OF MERGER This AGREEMENT AND PLAN OF MERGER (hereinafter

referred to as this “Agreement”), dated as of November 14, 2021, is by and among

American Tower Investments LLC, a California limited liability company and

subsidiary of Parent Guarantor (“Parent”), Appleseed Holdco LLC, a Delaware

limited liability company and wholly owned subsidiary of Parent (“Holdco”),

Appleseed Merger Sub LLC, a Maryland limited liability company and wholly owned

subsidiary of Holdco (“Purchaser”), Appleseed OP Merger Sub LLC, a Delaware

limited liability company and wholly owned subsidiary of Holdco (“OP Merger Sub”

and, together with Parent, Holdco and Purchaser, the “Parent Parties”), CoreSite

Realty Corporation, a Maryland corporation (the “Company”), CoreSite, L.P., a

Delaware limited partnership and subsidiary of the Company (the “Company

Operating Partnership”) and, solely for purposes of Section 2.4(c), Section

2.4(e), Section 4.1, Section 4.2, Section 4.4, Section 4.5(a)(ii), Section

4.5(c), Section 4.5(d), Section 4.5(e), Section 4.9, Section 4.12, Section 6.3,

Section 6.13, Section 6.14 and Article IX, American Tower Corporation, a

Delaware corporation (“Parent Guarantor”). All capitalized terms used in this

Agreement shall have the meaning ascribed to such terms in Section 9.5 or as

otherwise defined elsewhere in this Agreement unless the context clearly

provides otherwise. Parent, Holdco, Purchaser, OP Merger Sub, the Company

Operating Partnership, the Company and Parent Guarantor are each sometimes

referred to herein as a “Party” and collectively as the “Parties.” RECITALS

WHEREAS, on the terms and subject to the conditions set forth in this Agreement,

Purchaser will commence a cash tender offer (as it may be amended from time to

time as permitted under this Agreement, the “Offer”) to purchase any and all of

the outstanding shares of common stock, par value $0.01 per share, of the

Company (the “Company Common Stock” or “Company Shares”), at a price per Company

Share equal to the Merger Consideration, without interest and subject to any

applicable withholding Taxes (such amount, or any higher amount per Company

Share that may be paid pursuant to the Offer, the “Offer Price”), net to the

seller in cash; WHEREAS, following the consummation of the Offer, the Parties

wish to effect a merger of Purchaser with and into the Company, with the Company

being the surviving entity (the “Company Merger”), with the Company Merger to be

effected pursuant to Section 3-106.1 of the Maryland General Corporation Law

(the “MGCL”) without the approval of the Company’s stockholders; WHEREAS, in

the Company Merger, each Company Share issued and outstanding immediately prior

to the Company Merger Effective Time (other than Company Shares acquired

pursuant to the Offer) will be converted into the right to receive the Merger

Consideration, upon the terms and conditions set forth in this Agreement and in

accordance with the MGCL and the Maryland Limited Liability Company Act (the

“MLLCA”); WHEREAS, immediately following the Company Merger but after the

Partnership Merger, Parent will cause the Interim Surviving Entity to merge with

and into Holdco, with Holdco being the surviving entity (the “Holdco Merger”);

WHEREAS, the Parties also wish to effect a merger of the Company Operating

Partnership in connection with, and substantially simultaneously with, the

consummation of the Company Merger (but preceding the Holdco Merger), in which

OP Merger Sub shall merge with and into the Company Operating Partnership with

the Company Operating Partnership being the surviving entity (the “Partnership

Merger” and, together with the Company Merger and Holdco Merger, the “Mergers”),

and each outstanding Company Partnership Unit held by a Person other than the

Company immediately prior to the Partnership Merger Effective Time will be

converted into the right to receive the Merger Consideration, upon the terms and

conditions set forth in this Agreement and in accordance with the Delaware

Revised Uniform Limited Partnership Act (the “DRULPA”) and the Delaware Limited

Liability Company Act (the “DLLCA”);