Funds held for clients and corporate investments consisted of the following:

Money market securities and other cash equivalents as of November 30, 2011 and May 31, 2011 include money market funds, FDIC-insured deposit accounts, and other bank demand deposit accounts. In addition, included in other cash equivalents as of May 31, 2011 were U.S. agency discount notes and a municipal bond with a maturity of less than 90 days when acquired. Within bank demand deposit accounts for funds held for clients, the Company maintained $10.7 million as of November 30, 2011 and $16.7 million as of May 31, 2011 in a separately designated account for tax obligations of a partner’s clients.

Classification of investments on the Consolidated Balance Sheets is as follows:

The Company’s available-for-sale securities reflected a net unrealized gain of $53.7 million as of November 30, 2011 compared with a net unrealized gain of $59.3 million as of May 31, 2011. Included in the net unrealized gain as of November 30, 2011 and May 31, 2011, there were, respectively, 28 and 15 available-for-sale securities in an unrealized loss position. The securities in an unrealized loss position, all in a loss position for less than twelve consecutive months, were as follows:

The Company regularly reviews its investment portfolios to determine if any investment is other-than-temporarily impaired due to changes in credit risk or other potential valuation concerns. The Company believes that the investments it held as of November 30, 2011, with unrealized losses of $0.3 million, were not other-than-temporarily impaired. The Company believes that it is probable that the principal and interest will be collected in accordance with the contractual terms, and that the unrealized losses on these securities were due to changes in interest rates, and were not due to increased credit risk or other valuation concerns. All of the securities in an unrealized loss position as of November 30, 2011 and May 31, 2011 held an AA rating or better. The Company intends to hold these investments until the recovery of their amortized cost basis or maturity and it is more likely than not that the Company will not be required to sell these investments prior to that time. The Company’s assessment that an investment is not other-than-temporarily impaired could change in the future due to new developments or changes in the Company’s strategies or assumptions related to any particular investment.

Realized gains and losses on the sales of securities are determined by specific identification of the amortized cost basis of each security. On the Consolidated Statements of Income, realized gains and losses from funds held for clients are included in interest on funds held for clients and realized gains and losses from corporate investments are included in investment income, net. Realized gains were $0.1 million and $0.2 million for the three and six months ended November 30, 2011, compared with $0.2 million and $0.3 million for the three and six months ended November 30, 2010. There were no gross realized losses during the related periods.

The amortized cost and fair value of available-for-sale securities that had stated maturities as of November 30, 2011 are shown below by contractual maturity. Expected maturities can differ from contractual maturities because borrowers may have the right to prepay obligations without prepayment penalties.

Variable rate demand notes are primarily categorized as due after five years in the table above as the contractual maturities on these securities are typically 20 to 30 years. Although these securities are issued as long-term securities, they are priced and traded as short-term instruments because of the liquidity provided through the tender feature.