8. Unsecured Senior Notes

The following summarizes the unsecured senior notes outstanding as of December 31, 2015 (dollars in thousands) (See also Note 20):



	Coupon/ Stated Rate		Effective Rate(1)		Principal Amount			Maturity Date(2)
10 Year Unsecured Senior Notes	5.875	%	5.967	%	$	700,000		October 15, 2019
10 Year Unsecured Senior Notes	5.625	%	5.708	%	700,000			November 15, 2020
10 Year Unsecured Senior Notes	4.125	%	4.289	%	850,000			May 15, 2021
7 Year Unsecured Senior Notes	3.700	%	3.853	%	850,000			November 15, 2018
11 Year Unsecured Senior Notes	3.850	%	3.954	%	1,000,000			February 1, 2023
10.5 Year Unsecured Senior Notes	3.125	%	3.279	%	500,000			September 1, 2023
10.5 Year Unsecured Senior Notes	3.800	%	3.916	%	700,000			February 1, 2024
Total principal					5,300,000
Net unamortized discount					(10,683		)
Total					$	5,289,317

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(1)	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.


(2)	No principal amounts are due prior to maturity.

The indenture relating to the unsecured senior notes contains certain financial restrictions and requirements, including (1) a leverage ratio not to exceed 60%, (2) a secured debt leverage ratio not to exceed 50%, (3) an interest coverage ratio of greater than 1.50, and (4) an unencumbered asset value of not less than 150% of unsecured debt. At December 31, 2015, Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements.