(13)	EARNINGS PER SHARE

The following table presents the components of basic and diluted earnings per share for the three months ended March 31, 2019 and 2018 (in thousands, except per share amounts):

	Three months ended March 31,
	2019			2018
Net earnings attributable to Kirby	$	44,296		$	32,471
Undistributed earnings allocated to restricted shares		(119	)		(156	)
Income available to Kirby common stockholders – basic		44,177			32,315
Undistributed earnings allocated to restricted shares		119			156
Undistributed earnings reallocated to restricted shares		(119	)		(156	)
Income available to Kirby common stockholders – diluted	$	44,177		$	32,315

Shares outstanding:
Weighted average common stock issued and outstanding		59,869			59,678
Weighted average unvested restricted stock		(160	)		(286	)
Weighted average common stock outstanding – basic		59,709			59,392
Dilutive effect of stock options and restricted stock units		114			101
Weighted average common stock outstanding – diluted		59,823			59,493

Net earnings per share attributable to Kirby common stockholders:
Basic	$	0.74		$	0.54
Diluted	$	0.74		$	0.54

Certain outstanding options to purchase approximately 479,000 and 467,000 shares of common stock were excluded in the computation of diluted earnings per share as of March 31, 2019 and 2018, respectively, as such stock options would have been antidilutive. Certain outstanding RSUs to convert to 1,000 shares of common stock were also excluded in the computation of diluted earnings per share as of March 31, 2019 as such RSUs would have been antidilutive.