Transactions Table

Jeffrey S. Finnin is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may continue.

Explanation of Responses:

Id	Content
F1	In connection with the consummation of the Company Merger (as defined below), the Compensation Committee of the Board of Directors of CoreSite Realty Corporation (the "Company") certified the level of achievement of the performance goals applicable to each award of performance-based restricted shares (each, a "Company Performance Stock Award"), which resulted in an increase in the number of shares of common stock, par value $0.01 per share ("Company Common Stock") underlying the Company Performance Stock Awards granted in 2019.
F2	In connection with the consummation of the Company Merger, at the Company Merger Effective Time (as defined below), each share of Company Common Stock, of 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.
F3	At the Company Merger Effective Time, 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.
F4	At the Company Merger Effective Time, each Company Performance 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 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 Performance Stock Award as of immediately prior to the Effective Time and (B) the Offer Price.
F5	The reporting person's spouse is the trustee of the family trust.

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 Corporation. 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.