We pay our non-executive directors annual fees of $70,000, plus reimbursement for their out-of-pocket expenses, which amounts are payable at the election of each non-executive director in cash or stock as described below under “— Equity Compensation Plan.” The audit committee chairman receives an additional annual fee of $15,000. For each of the years ended December 31, 2022 and 2023, non-executive directors received an additional bonus award of $147,500 in the aggregate. Executive officers serving as directors receive no compensation for their services as a director. We do not have service contracts with any of our non-employee directors. We have employment agreements with one director who is also an executive officers of our company, as well as with our other three executive officers.
We directly employ our executive officers, who received aggregate cash compensation of $2.2 million (€2.0 million), $2.1 million (€2.0 million) and $2.1 million (€1.8 million) for the years ended December 31, 2023, 2022 and 2021, respectively. As of January 1, 2024, the annual base compensation of our executive officers is at €2.3 million in the aggregate. Our executive officers are also eligible, in the discretion of our board of directors and compensation committee, for incentive compensation and restricted stock, stock options or other awards under our equity compensation plan, which is described below under “— Equity Compensation Plan.” We recognized non-cash share-based compensation expense in respect of awards to executive officers of $6.3 million, $5.4 million and $11.8 million in the years ended December 31, 2023, 2022, and 2021, respectively.
In addition, effective from December 14, 2022, the Company maintains a defined benefit retirement plan for its executive officers. Prior service cost arising from the retrospective recognition of past service of $14.2 million was recognized in the “Other Comprehensive Income” in 2022, out of which advances amounting to $7.8 million were exercised and recognized under “Other income/(expense), net” in the Consolidated Statement of Income in the period ended December 31, 2022. In 2023, one additional executive officer was added to the plan and another one was appointed to a new position. Prior service cost arising from the retrospective recognition of past service and due to experience amounting to $5.2 million and losses due to assumptions change amounting to $1.1 million were recognized in “Other Comprehensive Income” in 2023. Defined benefit obligation of $13.3 million and $6.4 million is presented under “Other long-term liabilities” on the Company’s balance sheet as of December 31, 2023 and December 31, 2022, respectively.
Our executive officers are entitled to severance payments for termination without “cause” or for “good reason” generally equal to (i) (x) the greater of (A) the amount of base salary that would have been payable during the remaining term of the agreements, which expire in December 2027, and (B) three times the executive officer’s annual salary plus bonus (based on an average of the prior three years), including the value on the date of grant of any equity grants made under our equity compensation plan during that three-year period (which, for stock options, will be the Black-Scholes value), as well as (y) a pro-rata bonus for the year in which termination occurs and continued benefits, if any, for 36 months or (ii) if such termination without cause or for good reason occurs within two years of a “change of control” of our company the greater of (a) the amount calculated as described in clause (i) and (b) a specified dollar amount for each executive officer (approximately €6.8 million in the aggregate for all executive officers, excluding amounts payable under the defined benefit retirement plan), as well as continued benefits, if any, for 36 months.
Equity Compensation Plan
Our equity compensation plan allows the plan administrator to grant awards of shares of our common stock or the right to receive or purchase shares of our common stock (including restricted stock, stock options and other awards) to our employees, directors or other persons or entities providing significant services to us or our subsidiaries. The aggregate number of shares of common stock for which awards may be granted under the Plan shall not exceed 1,000,000 shares plus the number of shares subject to outstanding unvested awards granted before August 2, 2019. Awards made under the Plan that have been forfeited, cancelled or have expired, will not be treated as having been granted for purposes of the preceding sentence. These equity awards under our amended and restated 2006 equity compensation plan may be granted by the Company’s Compensation Committee or Board of Directors.
On September 14, 2018, the Company granted 298,774 shares of restricted stock to executive officers of the Company, out of which 149,386 restricted shares vested on December 31, 2019 and 149,388 restricted shares vested on December 31, 2021. On February 12, 2021, the Company granted 110,000 fully vested shares to executive officers and Board of Directors members. On December 10, 2021, the Company granted