Sec Form 4 Filing - Jones Mark R @ CoreSite Realty Corp - 2021-12-28

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person Jones Mark R 2. Issuer Name and Ticker or Trading Symbol CoreSite Realty Corp [ COR] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Accounting Officer (Last) (First) (Middle) C/O CORESITE REALTY CORPORATION, 1001 17TH STREET, SUITE 500 3. Date of Earliest Transaction (MM/DD/YY) 12/28/2021 (Street) DENVER, CO80202 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 12/28/2021 D 11,126( 1 )( 2 ) D 0 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Jones Mark R C /O CORESITE REALTY CORPORATION 1001 17TH STREET, SUITE 500 DENVER, CO80202 Chief Accounting Officer Signatures /s/ Derek S. McCandless, Attorney-in-Fact 12/29/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )In connection with the consummation of the Company Merger (as defined below), at the Company Merger Effective Time (as defined below), each share of common stock, par value $0.01 per share ("Company Common Stock"), of CoreSite Realty Corporation (the "Company") that was outstanding immediately prior to the Company Merger Effective Time (other than certain shares specified in the Merger Agreement (as defined below)) was automatically converted into the right to receive $170.00 in cash (the "Offer Price"), without interest and subject to required withholding taxes. ( 2 )At the Company Merger Effective Time, 20% of each award of time-based restricted shares ("Company Restricted Stock Award") that was outstanding as of immediately prior to the Company Merger Effective Time vested and all restrictions thereupon lapsed, and each such award was cancelled and converted into the right to receive a cash payment equal to the product of (A) the number of shares of Company Common Stock underlying such Company Restricted Stock Award as of immediately prior to the Effective Time and (B) the Offer Price. The remaining 80% of Company Restricted Stock Awards that were outstanding as of immediately prior to the Company Merger Effective Time were assumed by American Tower Corporation ("American Tower") and converted into awards of restricted shares of American Tower common stock, par value $0.01 per share ("American Tower Common Stock" and each award, the "American Tower Restricted Stock Award") in accordance with the terms of the Merger Agreement.

Remarks: This Form 4 reports securities disposed of under the terms of the Agreement and Plan of Merger (as amended or supplemented from time to time, the "Merger Agreement"), dated as of November 14, 2021, by and among the Company, CoreSite, L.P. ("Partnership"), Appleseed Merger Sub LLC ("Purchaser"), American Tower Investments LLC ("Parent"), Appleseed Holdco LLC ("Holdco"), Appleseed OP Merger Sub LLC ("OP Merger Sub") and, solely for the purposes of certain provisions specified therein, American Tower. Pursuant to the Merger Agreement, on December 28, 2021, (i) Purchaser merged with and into the Company, with the Company surviving as a wholly owned subsidiary of Holdco (the "Company Merger", and the effective time of such merger, the "Company Merger Effective Time"); (ii) substantially simultaneously with the Merger but preceding the Holdco Merger, OP Merger Sub merged with and into the Partnership, with the Partnership continuing as the surviving limited partnership (the "Partnership Merger"); and (iii) immediately following the Company Merger but after the Partnership Merger, the Company merged with and into Holdco, with Holdco continuing as the surviving limited liability company. A copy of the Merger Agreement is included as Exhibit 2.1 to the Company's Form 8-K filed with the SEC on November 14, 2021.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.