D.  Investment Risk Concentration The following table shows investments in any person and its af filiates that exceed 10% of total stockholders’  equity as of  December 31, 2012: Securities Classifications Market Value Municipal Securities Corporate Bonds US Treasury  Money  Market Equity Other  Invested  Assets ($ in thousands) $ % Issuer Description Northern Institutional Treasury Portfolio . . . $ 258,560 5.0% $ — $ — $ 258,560 $ — $ — State of Illinois . . . . . . . . . . . . . . . . . . . . . . . 138,414 2.7 138,414 — — — — Citigroup Inc. . . . . . . . . . . . . . . . . . . . . . . . . 134,507 2.6 — 111,092 — 23,415 — BlackRock Liquidity Funds T-Fund  Portfolio Money Market . . . . . . . . . . . . . . . . 133,391 2.6 — — 133,391 — — Bank of America Corp . . . . . . . . . . . . . . . . . 114,424 2.2 — 111,054 — 3,370 — Vanguard Institutional Index Fund . . . . . . . . 98,913 1.9 — — — 98,913 — State of California . . . . . . . . . . . . . . . . . . . . . 91,269 1.8 91,269 — — — — STIT Treasury Portfolio Cash Management  Fund . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84,018 1.6 — — 84,018 — — Federated Treasury Obligations Fund . . . . . . 81,507 1.6 — — 81,507 — — Wells Fargo & Co . . . . . . . . . . . . . . . . . . . . . 81,463 1.6 — 81,463 — — — Fidelity Institutional Treasury Only Portfolio . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80,570 1.5 — — 80,570 — — The Royal Bank of Scotland Group plc . . . . 78,006 1.5 — — — — 78,006 Top Investment Portfolio Risk Concentrations . . . . . . . . . . . . . . . . . . . . . . . $ 1,375,042 26.6% $ 229,683 $ 303,609 $ 638,046 $ 125,698 $ 78,006 42