	Three months ended March 31,
	2021			2020
	(In thousands)
Common stock, beginning of period	$	39,306		$	41,207
Shares issued for stock options exercised		-			-
Shares of common stock issued upon lapse of restricted stock units (“RSUs”)		150			183
Common stock retired		(42	)		(930	)
Common stock, end of period	$	39,414		$	40,460

The above reconciliation excludes RSUs and performance-based stock units (“PSUs”), which do not have voting rights. As sales restrictions on RSUs lapse and PSUs are earned, we issue common shares with voting rights. As of March 31, 2021, we had a total of 270,136 RSUs and 73,062 PSUs outstanding. The PSU outstanding balance is based on the number of PSUs granted pursuant to the award agreements; however, the actual number of common shares issued could be higher or lower based on actual versus targeted performance. See Note 9 (Share-Based Transactions) for discussion of the PSU award structure.

On February 10, 2020, our Board of Directors authorized a share repurchase program (“Prior Share Repurchase Program”) for up to $300.0 million of our outstanding common stock for purchases through June 30, 2021. On February 9, 2021, our Board of Directors authorized a new share repurchase program (“Share Repurchase Program”) for up to $300.0 million of our outstanding common stock (including $68.6 million remaining from the Prior Repurchase Program) for purchases through June 30, 2022. We are under no obligation to repurchase shares under the Share Repurchase Program. There were no repurchases during the quarter and as a result,

$300.0 million remains available for repurchases of our outstanding common stock under the Share Repurchase Program as of March 31, 2021.