Basic earnings per share are based on the weighted average number of common shares outstanding during the period. Diluted earnings per share are based on the weighted average number of common shares outstanding during the period adjusted to give effect to common stock equivalents.

The following table sets forth the computation of basic and diluted earnings per share for the periods indicated (in thousands, except per share data):


	Three months ended June 30,						Six months ended June 30,
	2023			2022			2023			2022
Basic and Diluted:
Net income attributable to UHS	$	171,313		$	164,062		$	334,428		$	317,975
Less: Net income attributable to unvested restricted share grants		(61	)		(164	)		(190	)		(413	)
Net income attributable to UHS – basic and diluted	$	171,252		$	163,898		$	334,238		$	317,562

Weighted average number of common shares - basic		70,073			73,682			70,304			74,356
Net effect of dilutive stock options and grants based on the treasury stock method		766			753			859			882
Weighted average number of common shares and equivalents - diluted		70,839			74,435			71,163			75,238
Earnings per basic share attributable to UHS:	$	2.44		$	2.22		$	4.75		$	4.27
Earnings per diluted share attributable to UHS:	$	2.42		$	2.20		$	4.70		$	4.22

The “Net effect of dilutive stock options and grants based on the treasury stock method”, for all periods presented above, excludes certain outstanding stock options applicable to each period since the effect would have been anti-dilutive. The excluded weighted-average stock options totaled 5.2 million for the three and six-months ended June 30, 2023. The excluded weighted-average stock options totaled 5.6 million for the three and six-months ended June 30, 2022. All classes of our common stock have the same dividend rights.

During the three-month periods ended June 30, 2023 and 2022, pre-tax compensation costs of $15.9 million and $17.6 million, respectively, was recognized related to outstanding stock options. During the six-month periods ended June 30, 2023 and 2022, pre-tax compensation costs of $32.1 million and $32.8 million, respectively, was recognized related to outstanding stock options. In addition, during the three-month periods ended June 30, 2023 and 2022, pre-tax compensation cost of approximately $5.8 million and $4.7 million, respectively, was recognized related to restricted stock awards, restricted stock units and performance based restricted stock units. During the six-month periods ended June 30, 2023 and 2022, pre-tax compensation cost of approximately $10.3 million and $8.1 million, respectively, was recognized related to restricted stock awards, restricted stock units and performance based restricted stock units. As of June 30, 2023 there was approximately $204.4 million of unrecognized compensation cost related to unvested options, restricted stock awards, restricted stock units and performance based restricted stock units which is expected to be recognized over the remaining weighted average vesting period of 2.8 years. There were 1,893,756 stock options granted during the first six months of 2023 with a weighted-average grant date fair value of $41.81 per option. There were an aggregate of 287,757 restricted units granted during the first six months of 2023, including 93,606 performance based restricted stock units, with a weighted-average grant date fair value of $118.14 per share.

The expense associated with stock-based compensation arrangements is a non-cash charge. In the Condensed Consolidated Statements of Cash Flows, stock-based compensation expense is an adjustment to reconcile net income to cash provided by operating activities and aggregated to $43.1 million and $41.6 million during the six-month periods ended June 30, 2023 and 2022.