For the three and six months ended October 31, 2018, we excluded options to purchase 12,000 and 6,065 Class A Common Shares, respectively, and for the three and six months ended October 31, 2017, we excluded options to purchase 1,184,124 and 1,105,521 Class A Common Shares, respectively, from the computation of diluted earnings per Class A Common Shares. We excluded these option share amounts because the exercise prices of those options were greater than the average market price of the Class A Common Shares during the applicable period. As of October 31, 2018, we had a total of 4,119,923 options outstanding and as of October 31, 2017, we had a total of 3,440,512 options outstanding.
E. Stock-Based Compensation
During the six months ended October 31, 2018 and 2017, we granted options for 1,189,000 and 884,000 shares of Class A common stock, respectively. The fair value of each option award is estimated on the date of grant using the Black-Scholes option pricing model. The forfeiture rates are estimated using historical data. We recorded stock option compensation cost of approximately $443,000 and $477,000 and income tax excess benefits of approximately $12,000 and shortfall of $47,000 from option exercises during the three months ended October 31, 2018 and 2017, respectively. We recorded stock option compensation cost of approximately $841,000 and $793,000, and income tax excess benefits of approximately $286,000 and $80,000 from option exercises during the six months ended October 31, 2018 and 2017, respectively. We record stock-based compensation expense on a straight-line basis over the vesting period directly to additionalpaid-in capital.
During the six months ended October 31, 2018 and 2017, we issued 343,000 and 482,000 shares of Class A common stock, respectively, resulting from the exercise of stock options. The total intrinsic value of options exercised during the six months ended October 31, 2018 and 2017 based on market value at the exercise dates was approximately $1.9 million and $1.3 million, respectively. As of October 31, 2018, unrecognized compensation cost related to unvested stock option awards approximated $5.4 million, which we expect to recognize over a weighted average period of 2.04 years.
F. Fair Value of Financial Instruments
We measure our investments based on a fair value hierarchy disclosure framework that prioritizes and ranks the level of market price observability used in measuring assets and liabilities at fair value. A number of factors affect market price observability, including the type of asset or liability and its characteristics. This hierarchy prioritizes the inputs into three broad levels as follows:
| • | | Level 1—Quoted prices for identical instruments in active markets. |
| • | | Level 2—Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. |
| • | | Level 3—Valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. |
The following is a general description of the valuation methodologies we use for financial assets and liabilities measured at fair value, including the general classification of such assets and liabilities pursuant to the valuation hierarchy.
Cash Equivalents—Cash equivalents include investments in government obligation based money-market funds, other money market instruments and interest-bearing deposits with initial terms of three months or less. The fair value of cash equivalents approximates its carrying value due to the short-term nature of these instruments.
Marketable Securities—Marketable securities utilizing Level 1 inputs include active exchange-traded equity securities and equity index funds, and most U.S. Government debt securities, as these securities all have quoted prices in active markets. Marketable securities utilizing Level 2 inputs include municipal bonds. We value these securities using market-corroborated pricing or other models that use observable inputs such as yield curves.
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