In conjunction with the Spin-Off and IPO, notes payable to certain former stockholders of MMREIS were issued in settlement of restricted stock and SARs awards that were redeemed by MMREIS upon the termination of employment by these former stockholders (“the Notes”). The Notes had been previously assumed by MMC, and were transferred to the Company. The Notes are unsecured and bear interest at 5% with annual principal and interest installments and a final principal payment due during the second quarter of 2020. During each of the years ended December 31, 2017 and 2016, the Company made total payments on the Notes, including interest, of $1.5 million.

Accrued interest included in accounts payable and accrued expenses in the accompanying consolidated balance sheets pertaining to the Notes consisted of the following (in thousands):

Interest expense pertaining to the Notes consisted of the following (in thousands):

Future minimum principal payments on the Notes consisted of the following (in thousands):