C. Available-for-sale investments:

At June 30, 2012 and 2011, the amortized cost and market value of the Company’s available-for-sale securities by major security type were as follows (in thousands):

At June 30, 2012 and 2011, all of the Company’s available-for-sale investments were valued using Level 1 inputs. Gross unrealized gains and unrealized losses on available-for-sale investments were $66.3 million and $33,000, respectively, at June 30, 2012. Gross unrealized gains and unrealized losses on available-for-sale investments were $1.1 million and $58,000, respectively, at June 30, 2011.

The Company’s investment in equity securities consists of investments in the common stock and warrants of ChemoCentryx, Inc. (CCXI). At June 30, 2011, the Company had a $14.3 million investment in the preferred stock of CCXI and accounted for the investment on a cost basis. The investment was included in “Investments in unconsolidated entities” at June 30, 2011. In September 2011, the Company entered into a $10.0 million loan agreement with CCXI. The loan was carried at fair value (Level 3 input) while outstanding. The loan agreement contained a number of conversion features contingent upon CCXI obtaining future debt or equity financing. The agreement also included a $5.0 million commitment by the Company to participate in a private placement in the event of a successful public offering of CCXI shares. On February 8, 2012, CCXI completed its initial public offering (IPO) at $10 per share. Upon the close of the IPO, the Company’s investment in CCXI’s preferred shares and the loan, plus accrued interest, converted into CCXI common stock. The Company invested an additional $5.0 million in the private placement, as discussed above, and received ten year warrants to purchase 150,000 shares of CCXI common stock at $20 per share. At June 30, 2012, the Company holds an approximate 18.0% interest in CCXI.

Activity related to available-for-sale investments with Level 3 inputs were as follows (in thousands):

Unrealized gains and losses on the Company’s available-for-sale debt securities are caused by interest rate changes. The Company has the ability and intent to hold its available-for-sale investments that are in an unrealized loss position until a recovery of fair value. The Company does not consider these investments to be other-than-temporarily impaired at June 30, 2012.

At June 30, 2012, the Company’s investments in an unrealized loss position that have been determined to be temporarily impaired were as follows (in thousands):

Contractual maturities of available-for-sale debt securities are shown below (in thousands). Expected maturities may differ from contractual maturities because borrowers may have the right to recall or prepay obligations with or without call or prepayment penalties.

Proceeds from maturities or sales of available-for-sale securities were $131.7 million, $173.5 million and $66.6 million during fiscal 2012, 2011 and 2010, respectively. There were no material realized gains or losses on these sales. Realized gains and losses are determined on the specific identification method.