(3) Investment Securities A summary of investment securities available-for-sale is as follows:  74  (Dollars in thousands) Gross Gross Amortized unrealized unrealized Estimated cost gains losses fair value U. S. federal agency obligations 8,804 $ 50 $ (6) $ 8,848 $ Municipal obligations, tax exempt 73,699 3,618 (31) 77,286 Municipal obligations, taxable 37,334 818 (10) 38,142 Mortgage-backed securities 81,113 889 (154) 81,848 Common stocks 602 301 (1) 902 Certificates of deposit  6,274 - - 6,274 Total 207,826 $ 5,676 $ (202) $ 213,300 $ As of December 31, 2012 Gross Gross Amortized unrealized unrealized Estimated cost gains losses fair value U. S. federal agency obligations 9,120 $ 44 $ - $ 9,164 $ Municipal obligations, tax exempt 65,404 4,226 (1) 69,629 Municipal obligations, taxable 18,961 243 (69) 19,135 Mortgage-backed securities 92,742 1,823 (93) 94,472 Common stocks 621 198 - 819 Pooled trust preferred securities 1,104 - (699) 405 Certificates of deposit  4,590 - - 4,590 Total 192,542 $ 6,534 $ (862) $ 198,214 $ As of December 31, 2011