Leasing Activity

Future minimum base rental payments of our office properties due to us under non-cancelable leases in effect as of December 31, 2015 for our consolidated properties are as follows (in thousands):



Year	Future Minimum Base Rental Payments
2016	$	13,165
2017	11,954
2018	5,312
2019	3,751
2020	2,994
2021	2,364
2022	1,913
2023	1,511
2024	976
2025	957
Thereafter	660
Total	$	45,557

The schedule above does not include rental payments due to us from our multifamily, hotel and student housing properties, as leases associated with these properties typically are for periods of one year or less. We have excluded Las Colinas Commons, our office building located in Texas, from the schedule above as it was classified as held for sale at December 31, 2015.

Significant Tenants

As of December 31, 2015, we had one lease that accounted for 10% or more of our aggregate annual rental revenue from our consolidated office properties. Northborough Tower, a single-tenant office building accounted for $5.7 million (or 40%) of our aggregate annual rental revenue from our consolidated office properties, and 11% of our total revenues, excluding revenues for Las Colinas Commons which was classified as real estate held for sale as of December 31, 2015. During the third quarter of 2015, Northborough Tower’s single tenant vacated the building. The tenant’s lease does not expire until April 2018, and the tenant has continued to make its monthly rental payment. We did not pay the outstanding principal balance of the loan at maturity, January 11, 2016, which constituted an event of default. The cash management agreement provides that upon an event of default, the lender can cause all funds in the property account, consisting primarily of tenant rental payments, to be deposited into a lender-controlled and administered bank account to be applied to the outstanding principal balance. In December 2015, the lender exercised its right to control the operating funds of the property. The lender has been funding the operations of the property from the tenant rental funds and indicated they expect to continue to do so. The loan is non-recourse to the Company and we have been in discussions with the lender’s special servicer to transfer the asset to the lender. On February 5, 2016, we received a notice from the lender of their intent to increase the interest on the Northborough loan to the default interest rate of 8.67%, effective January 12, 2016, due to the maturity default. On March 15, 2016, we received notice that Northborough Tower had been posted for foreclosure on April 5, 2016. The balance of the nonrecourse debt, secured by Northborough, was $18.5 million at December 31, 2015. The carrying value of the asset was $15.2 million at December 31, 2015.

Geographic Concentration

At any one time, a significant portion of our consolidated investments could be in one property class or concentrated in one or several geographic regions. For the year ended December 31, 2015, excluding revenue of $2.7 million for Las Colinas Commons, which was classified as real estate held for sale as of December 31, 2015, and mineral rights we received in 2015 of less than $0.1 million on a parcel of land we sold in 2013, 60%, 32% and 8% of our total revenues were derived from properties in Missouri, Texas and Colorado, respectively. Additionally, excluding revenue of $2.7 million for Las Colinas Commons, which was classified as real estate held for sale as of December 31, 2015, and mineral rights we received in 2015 of less than $0.1 million on a parcel of land we sold in 2013, 68%, 28% and 4% of our total revenues for the year ended December 31, 2015 were from our three asset types, hotel, office building and multifamily. To the extent that our portfolio is concentrated in limited geographic regions, types of assets, industries or business sectors, downturns relating generally to such region, type of asset, industry or business sector may result in defaults by our tenants within a short time period, which may reduce our net income and the value of our common stock and accordingly limit our ability to fund our operations.

Excluding revenue of $2.7 million for Las Colinas Commons, which was classified as real estate held for sale as of December 31, 2015, and mineral rights we received in 2015 of less than $0.1 million on a parcel of land we sold in 2013, three of our consolidated properties represented more than 10% of our 2015 total revenue: Chase Park Plaza at 60%; Frisco Square at 14%; and Northborough Tower at 11%. During the third quarter of 2015, Northborough Tower’s single tenant vacated the building. The tenant’s lease does not expire until April 2018, and the tenant has continued to make its monthly rental payment. The cash management agreement provides that upon an event of default, the lender can cause all funds in the property account to be deposited into a lender-controlled and administered bank account. In December 2015, the lender exercised its right to control the operating funds of the property. See Note 9, Notes Payable, for additional information.