On August 17, 2016, Boston Properties, Inc.s operating partnership, Boston
Properties Limited Partnership (the Company), completed the issuance and sale of $1.0 billion aggregate principal amount of the Companys 2.750% Senior Notes due 2026 (the Notes) pursuant to an underwriting agreement
dated August 8, 2016 (the Underwriting Agreement), by and among the Company and Deutsche Bank Securities Inc., J.P. Morgan Securities LLC, Merrill Lynch, Pierce, Fenner & Smith Incorporated, Morgan Stanley & Co.
LLC and U.S. Bancorp Investments, Inc., as managers of the several underwriters named in Schedule II thereto (the Underwriters), whereby the Company agreed to sell and the Underwriters agreed to purchase from the Company, subject to and
upon the terms and conditions set forth in the Underwriting Agreement, the Notes.
The net proceeds to the Company from the sale of the Notes, after
deducting underwriting discounts and estimated transaction expenses, are estimated to be approximately $984.6 million. Concurrently with the closing of the offering, the Company used approximately $49.3 million of the net proceeds to settle certain
forward-starting interest rate swap contracts that fixed the 10-year swap rate at a weighted-average rate of approximately 2.423% per annum on notional amounts aggregating $550.0 million. When the impact of these settlements is applied to the
Notes, the effective GAAP interest rate of the Notes is approximately 3.498% per annum.
The Company plans to use the remaining net proceeds from the
offering to fund the repayment of (i) a mortgage loan with an outstanding principal amount of approximately $344.8 million, which is secured by the Companys Embarcadero Center Four property in San Francisco, California, matures on
December 1, 2016 and has a stated interest rate of 6.10% per annum and (ii) a mortgage loan with an outstanding principal amount of $750.0 million, which is secured by the Companys 599 Lexington Avenue property in New York City,
matures on March 1, 2017 and has a stated interest rate of 5.57% per annum, both of which may be repaid without penalty beginning on September 1, 2016. The Company intends to use available cash to fund the balance of the total amount
needed to repay these mortgages.
The Notes were issued under the Indenture, dated as of December 13, 2002, between the Company and The Bank of New
York Mellon Trust Company, N.A. (as successor to The Bank of New York), as supplemented by Supplemental Indenture No. 16 (Supplemental Indenture No. 16) dated as of August 17, 2016.
The offer and sale of the Notes were registered with the Securities and Exchange Commission (the Commission) pursuant to a registration statement
on Form S-3 (File No. 333-196491-01) under the Securities Act of 1933, as amended (the Securities Act). The material terms of the Notes are described in a prospectus supplement filed by the Company with the Commission on
August 9, 2016 pursuant to Rule 424(b)(5) under the Securities Act.
Copies of the Underwriting Agreement, Supplemental Indenture No. 16
and the form of the Notes are attached hereto as Exhibit 1.1, Exhibit 4.1 and Exhibit 4.2, respectively, and are incorporated herein by reference. The foregoing summaries do not purport to be complete and are qualified in their entirety by reference
to the Underwriting Agreement, Supplemental Indenture No. 16 and the form of the Notes.
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Additionally, in connection with the filing of the Underwriting Agreement, the Company is filing the opinion and
consent of its counsel, Goodwin Procter LLP, regarding the legality of the securities being registered as Exhibits 5.1 and 23.1 hereto, respectively, which are incorporated by reference into the Registration Statement on Form S-3 (File
No. 333-196491-01).