Earnings per Share

6 Months Ended

Jun. 30, 2021

11. EARNINGS PER SHARE

We compute basic earnings per common share by dividing net income attributable to Core Laboratories N.V. by the weighted average number of common shares outstanding during the period. Diluted earnings per share includes the incremental effect of contingently issuable shares from performance and restricted stock awards, as determined using the treasury stock method. The following table summarizes the calculation of weighted average common shares outstanding used in the computation of diluted earnings per share (in thousands):


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2021		2020		2021		2020
Weighted average common shares outstanding - basic		46,319		44,470		45,751		44,459
Effect of dilutive securities:
Performance shares		578		—		566		—
Restricted shares		206		—		197		—
Weighted average common shares outstanding - assuming dilution		47,103		44,470		46,514		44,459

For the three and six months ended June 30, 2020, the number of outstanding performance and restricted shares of Core Laboratories N.V. common shares that were excluded from the diluted earnings per share calculation, as their impact would be antidilutive, were as follows (in thousands):


	Three Months Ended		Six Months Ended
	June 30, 2020		June 30, 2020
Performance shares		187		315
Restricted shares		51		60