regulations which may differ from generally accepted accounting principles. Financial statements are adjusted for permanent book-tax differences; for the year ended December 31, 2022 such adjustments were approximately $456,000 primarily due to non-deductible employee compensation.
4. Investment Transactions—The aggregate cost of securities purchased and the aggregate proceeds of securities sold during the year ended December 31, 2022, excluding short-term investments, were $4,184,112 and $100,654,762, respectively.
As of December 31, 2022, the tax cost of investments was $463,213,806. Net unrealized appreciation was $668,155,780 consisting of gross unrealized appreciation and gross unrealized depreciation of $703,834,664 and $35,678,884, respectively.
5. Affiliated Companies—Plymouth Rock is an affiliated company as defined in the Investment Company Act of 1940 due to the Corporation’s ownership of 5% or more of the company’s outstanding voting securities. During the year ended December 31, 2022, unrealized appreciation from the Corporation’s investment in Plymouth Rock decreased by $34,108,800 and the Corporation received dividends of $9,344,958 from Plymouth Rock. The Chairman of the Corporation is a director of Plymouth Rock. The Chief Executive Officer and President of the Corporation is a director of certain subsidiaries of Plymouth Rock.
6. Restricted Securities—The Corporation may from time to time invest in securities the resale of which is restricted. On December 31, 2022, the Corporation’s only restricted security was 28,424 shares of Plymouth Rock Class A stock that were acquired on December 15, 1982 at a cost of $710,600. This security had an estimated fair value of $258,658,400 at December 31, 2022, which was equal to 22.8% of the Corporation’s net assets. The Corporation does not have the right to demand registration of this security.
7. Bank Line of Credit—The Corporation has entered into a $25 million uncommitted, secured revolving line of credit with UMB Bank, n.a. (“UMB”), the Corporation’s custodian. All borrowings are payable on demand of UMB. Interest on any borrowings is payable monthly at a rate based on the federal funds rate, subject to a minimum annual rate of 2.50%. No borrowings were made during the year ended December 31, 2022.
8. Compensation and Benefit Plans—The aggregate remuneration paid to all officers during the year ended December 31, 2022 was $3,433,000.
Officers and other employees participate in a 401(k) profit sharing plan. The Corporation has agreed to contribute 3% of each participant’s qualifying compensation to the plan, which is immediately vested. Contributions in excess of 3% may be made at the discretion of the Board of Directors and vest after three years of service. During the year ended December 31, 2022, the Corporation contributed $229,350 to the plan, which represented 15% of total qualifying compensation.
Until March 20, 2022, the Corporation maintained an incentive compensation plan (the “2012 Plan”) which permitted the granting of awards of unrestricted stock, restricted stock, restricted stock units and cash to full-time employees and non-employee directors of the Corporation. The 2012 Plan was administered by the Corporation’s Compensation and Nominating Committee.
Pursuant to the terms of the 2012 Plan, each non-employee director was awarded 500 shares of vested unrestricted Common Stock upon re-election at the Corporation’s annual meeting. During the year ended December 31, 2022, non-employee directors were granted a total of 3,500 shares of Common Stock at a grant date value of $40.58 per share. The value was the average of the high and low prices of the Corporation’s Common Stock on the grant date. The aggregate share value of $142,030 plus cash payments of $200,000 made to all non-employee directors are included in Directors’ fees expense in the accompanying Statement of Operations. No awards were made to employees during 2022.
9. Operating Lease—The Corporation leased office space under a lease that was scheduled to expire on June 30, 2022. The lease included fixed payments for occupancy and certain utilities and variable payments relating to the Corporation’s share of increases in building operating expenses and real estate taxes. Effective April 27,