NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts and where indicated as in millions or billions) At December 31, 2011 and 2010, we had investments in three and six mortgage and mezzanine loans, respectively, with an  aggregate carrying value of $162.8 million and $395.9 million, respectively. These loans mature at various dates through October  2012 with a weighted average maturity of approximately 6 months as of December 31, 2011. Certain of these loans require  interest-only payments while others require payments of interest and principal based on a 30 year amortization. Interest rates  on these loans are fixed between 5.9% and 7.0% per annum with a weighted average interest rate of approximately 6.3% and  approximate market rates for instruments of similar quality and duration. During 2011 and 2010, we recorded $24.3 million and  $4.6 million, respectively, in interest income earned from these loans held for investment. Payments on each of these loans were  current as of December 31, 2011. On December 9, 2011, we paid consideration of $88.8 million to acquire a 50% equity interest in two real estate developments  for which we had previously agreed to fund as the construction lender. The loans primarily bear interest at 7.0% and mature in May  and July 2013. At December 31, 2011, the aggregate amount drawn on the loans was $50.7 million. We consolidated these assets  as of the acquisition date and, accordingly, amounts drawn on the loans are eliminated in consolidation. The average life of in-place lease intangibles is approximately 4.4 years and is amortized over the remaining life of the leases  of the related property on the straight-line basis and is included with depreciation and amortization in the consolidated statements  of operations and comprehensive income. The amount of in-place lease intangibles increased during 2010 as a result of the  acquisition of Prime Outlets Acquisition Company, or the Prime acquisition, as further discussed in Note 4. The fair market value  of above and below market leases is amortized into revenue over the remaining lease life as a component of reported minimum  rents. The weighted average remaining life of these intangibles is approximately 4.0 years. The unamortized amount of below  market leases is included in accounts payable, accrued expenses, intangibles and deferred revenues in the consolidated balance  sheets and was $134.4 million and $39.0 million as of December 31, 2011 and 2010, respectively. The amount of amortization of  above and below market leases, net for the years ended December 31, 2011, 2010, and 2009 was $17.6 million, $15.2 million, and  $20.0 million, respectively. If a lease is terminated prior to the original lease termination, any remaining unamortized intangible is  charged to earnings. Details of intangible assets as of December 31 are as follows: Estimated future amortization and the increasing (decreasing) effect on minimum rents for our above and below market  leases as of December 31, 2011 are as follows: 42 Simon Property Group, Inc. Increase to Below Market  Above Market  Minimum Leases  Leases  Rent, Net 2012  $ 29,184  $ (14,212)  $  14,972 2013  23,612  (12,717)  10,895 2014  18,300  (11,067)  7,233 2015  15,842  (9,675)  6,167 2016  14,046  (8,797)  5,249 Thereafter  33,428  (19,482)  13,946 $ 134,412 $ (75,950) $ 58,462 2011 2010 In-place lease intangibles  $ 245,844 $ 211,541  Accumulated amortization  (45,746) (61,342) In-place lease intangibles, net  $ 200,098 $ 150,199  Acquired above market lease intangibles  $ 178,564 $ 104,690  Accumulated amortization  (102,614) (92,224) Acquired above market lease intangibles, net  $ 75,950  $ 12,466  Intangible Assets