On June 16, 2023, we completed a public offering of 6,053 shares of our Class A common stock at a public offering price of $85.50 per share. After deducting stock issuance costs, including underwriting discounts, commissions and offering expenses, the offering resulted in net proceeds of $496,231. The net proceeds from this offering were and are to be used to fund acquisition activity, including the GFL Acquisition and the Twin Bridges Acquisition, to pay certain costs associated with acquisition activities, as discussed in Note 18, Other Items and Charges, and to repay borrowings and/or debt securities as discussed Note 12, Debt.

The holders of the Class A common stock are entitled to one vote for each share held. The holders of the Class B common stock are entitled to ten votes for each share held, except for the election of one director, who is elected by the holders of the Class A common stock exclusively. The Class B common stock is convertible into Class A common stock on a share-for-share basis at the option of the shareholder.

2016 Incentive Plan. In the fiscal year ended December 31, 2016, we adopted the 2016 Incentive Plan (“2016 Plan”). Under the 2016 Plan, we may grant awards up to an aggregate amount of shares equal to the sum of: (i) 2,250 shares of Class A common stock (subject to adjustment in the event of stock splits and other similar events), plus (ii) such additional number of shares of Class A common stock (up to 2,723 shares) as is equal to the sum of the number of shares of Class A common stock that remained available for grant under the 2006 Stock Incentive Plan ("2006 Plan") immediately prior to the expiration of the 2006 Plan and the number of shares of Class A common stock subject to awards granted under the 2006 Plan that expire or otherwise result in shares not being issued.

As of December 31, 2023, there were 616 Class A common stock equivalents available for future grant under the 2016 Plan, inclusive of additional Class A common stock equivalents that were previously issued under terminated plans and have become available for grant because such awards expired or otherwise resulted in shares not being issued.

Stock options are granted at a price equal to the prevailing fair value of our Class A common stock at the date of grant. Generally, stock options granted have a term not to exceed ten years and vest over a one year to five-year period from the date of grant.

The fair value of each stock option granted is estimated using a Black-Scholes option-pricing model, which uses a risk-free interest rate, based on the U.S. Treasury yield curve for the period of the expected life of the stock option; and requires extensive use of accounting judgment and financial estimation, including estimates of: the expected term, calculated based on the weighted average historical life of the vested stock options, giving consideration to vesting schedules and historical exercise patterns; and the expected volatility, calculated using the weekly historical volatility of our Class A common stock over the expected life of the stock option.

Restricted stock awards and restricted stock units are granted at a price equal to the fair value of our Class A common stock at the date of grant. The fair value of each market-based performance stock unit is estimated using a Monte Carlo pricing model, which requires extensive use of accounting judgment and financial estimation, including the estimated share price appreciation plus the value of dividends of our Class A common stock as compared to the Russell 2000 Index over the requisite service period.

Restricted stock awards granted to non-employee directors vest incrementally over a three-year period beginning on the first anniversary of the date of grant. Restricted stock units granted to non-employee directors vest in full on the first anniversary of the grant date. Restricted stock units vest incrementally over an identified service period beginning on the grant date based on continued employment. Market-based performance stock units vest at a future date following the grant date and are based on the attainment of performance targets and market achievements.

A summary of stock option activity is as follows:


	Stock Options	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding, December 31, 2022	129	$	55.60
Granted	18	$	79.72
Exercised	(18)	$	4.88
Forfeited or expired	—	$	—

Outstanding, December 31, 2023	129	$	66.03	7.5	$	2,504
Exercisable, December 31, 2023	49	$	40.60	5.2	$	2,177

The fair value of stock options granted in fiscal year 2023 were calculated assuming no expected dividend yield using a weighted average expected life of 5.6 years, a risk-free interest rate of 4.6%, and an expected volatility of 30.0%.

The Black-Scholes valuation model requires extensive use of accounting judgment and financial estimation. Application of alternative assumptions could produce significantly different estimates of the fair value of stock-based compensation and consequently, the related amounts recognized in the consolidated statements of operations.

A summary of restricted stock award, restricted stock unit and performance stock unit activity is as follows:


	Restricted Stock Awards, Restricted Stock Units, and Performance Stock Units (1)	Weighted Average Grant Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding, December 31, 2022	169	$	75.52
Granted	121	$	80.99
Class A common stock vested	(101)	$	65.21
Forfeited or canceled	(8)	$	77.77
Outstanding, December 31, 2023	181	$	84.82	2.0	$	15,474
Unvested, December 31, 2023	288	$	87.35	1.9	$	24,593

(1)Performance stock unit grants are included at 100%. Attainment of maximum performance targets and market achievements would result in the issuance of an additional 107 shares of Class A common stock currently included in unvested. The market-based performance stock unit grants that vested in fiscal year 2023 resulted in the issuance of 43 additional shares of Class A common stock.

During fiscal years 2023, 2022 and 2021, stock-based compensation expense related to restricted stock awards, restricted stock units and performance stock units was $8,116, $7,530 and $11,241, respectively.

As of December 31, 2023, total unrecognized stock-based compensation expense related to outstanding restricted stock awards was $8, which will be recognized over a weighted average period of 0.5 years. As of December 31, 2023, total unrecognized stock-based compensation expense related to outstanding restricted stock units was $5,362, which will be recognized over a weighted average period of 2.3 years. As of December 31, 2023, total unrecognized stock-based compensation expense related to performance stock units based on our estimated achievement of the established performance criteria was $4,377, which will be recognized over a weighted average period of 1.6 years.

The weighted average fair value of market-based performance stock units granted during fiscal year 2023 was $83.16 per award, which was calculated using a Monte Carlo pricing model assuming a risk-free interest rate of 4.3% and an expected volatility of 34.9% assuming no expected dividend yield. Risk-free interest rate is based on the U.S. Treasury yield curve for the expected service period of the award. Expected volatility is calculated using the daily volatility of our Class A common stock over the expected service period of the award.

The Monte Carlo pricing model requires extensive use of accounting judgment and financial estimation. Application of alternative assumptions could produce significantly different estimates of the fair value of stock-based compensation and consequently, the related amounts recognized in the consolidated statements of operations.

We also recorded $451, $376 and $281 of stock-based compensation expense related to our Second Amended and Restated Employee Stock Purchase Plan (“ESPP”) during fiscal years 2023, 2022 and 2021, respectively.

Accumulated other comprehensive (loss) income, net of tax is a component of stockholders' equity included in the accompanying consolidated balance sheets and includes, as applicable, the effective portion of changes in the fair value of our cash flow hedges and the changes in fair value of our marketable securities.

The changes in the balances of each component of accumulated other comprehensive (loss) income, net of tax are as follows:


	Interest Rate Swaps
Balance as of December 31, 2020	$	(11,517)

Other comprehensive income before reclassifications	3,737
Amounts reclassified from accumulated other comprehensive loss	4,763
Income tax provision related to items in other comprehensive income	(2,086)
Other comprehensive income	6,414
Balance as of December 31, 2021	(5,103)

Other comprehensive income before reclassifications	15,297
Amounts reclassified from accumulated other comprehensive loss	1,443
Income tax provision related to items in other comprehensive income	(4,095)
Other comprehensive income	12,645
Balance as of December 31, 2022	7,542

Other comprehensive loss before reclassifications	(6,843)
Amounts reclassified from accumulated other comprehensive loss	(6,361)
Income tax benefit related to items in other comprehensive loss	4,582
Other comprehensive loss	(8,622)
Balance as of December 31, 2023	$	(1,080)

A summary of reclassifications out of accumulated other comprehensive (loss) income, net of tax for fiscal years 2023, 2022 and 2021 is as follows:


	Fiscal Year Ended December 31,
	2023		2022		2021
Details About Accumulated Other Comprehensive (Loss) Income, Net of Tax Components	Accumulated Other Comprehensive (Loss) Income, Net of Tax						Affected Line Item in the Consolidated Statements of Operations
Interest rate swaps	$	(6,361)	$	1,443	$	4,763	Interest expense
	6,361		(1,443)		(4,763)		Income before income taxes
	2,633		98		(1,142)		Provision for income taxes
	$	3,728	$	(1,541)	$	(3,621)	Net income