COMSTOCK RESOURCES, INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued) Reclassifications Use of Estimates in the Preparation of Financial Statements Concentration of Credit Risk and Accounts Receivable Marketable Securities Certain reclassifications have been made to prior periods’ financial statements consisting primarily of reclassifications to reflect the Company’s West Texas oil and gas properties as discontinued operations and a change in the presentation of our derivative financial instruments. The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual amounts could differ from those estimates. Changes in the future estimated oil and natural gas reserves or the estimated future cash flows attributable to the reserves that are utilized for impairment analysis could have a significant impact on the future results of operations. Financial instruments that potentially subject the Company to a concentration of credit risk consist principally of cash and cash equivalents, accounts receivable and derivative financial instruments. The Company places its cash with high credit quality financial institutions and its derivative financial instruments with financial institutions and other firms that management believes have high credit ratings. Substantially all of the Company’s accounts receivable are due from either purchasers of oil and gas or participants in oil and gas wells for which the Company serves as the operator. Generally, operators of oil and gas wells have the right to offset future revenues against unpaid charges related to operated wells. Oil and gas sales are generally unsecured. The Company’s policy is to assess the collectability of its receivables based upon their age, the credit quality of the purchaser or participant and the potential for revenue offset. The Company has not had any significant credit losses in the past and believes its accounts receivable are fully collectible. Accordingly, no allowance for doubtful accounts has been provided. As of December 31, 2012, the Company owned 600,000 shares of Stone Energy Corporation (“Stone”) common stock which was reflected in the consolidated balance sheets as marketable securities. During the year ended December 31, 2013 all of these shares were sold. As of December 31, 2012, the estimated fair value of the marketable securities was $12.3 million after recognizing an unrealized gain after income taxes of $4.4 million. The Company did not exert influence over the operating and financial policies of Stone, and classified its investment in these shares as an available-for-sale security in the consolidated balance sheet. Available-for-sale securities were accounted for at fair value, with any unrealized gains and unrealized losses not determined to be other than temporary reported in the consolidated balance sheet within accumulated other comprehensive income as a separate component of stockholders’ equity. The Company utilized the specific identification method to determine the cost of any securities sold. During each of 2011, 2012 and 2013, the Company sold 1,991,000, 1,206,000 and 600,000 shares of Stone common stock for proceeds of $53.4 million, $37.7 million and $13.4 million, respectively. Comstock realized gains before income taxes of $35.1 million, $26.6 million and $7.9 million on these sales during 2011, 2012 and 2013, respectively. F-10