Net Income (Loss) per Share

12 Months Ended

Dec. 31, 2023

15. Net Income (Loss) per Share

Basic and diluted net income (loss) per share attributable to common stockholders of Spero Therapeutics, Inc. was calculated as follows (in thousands, except share and per share amounts):



	Year Ended December 31,
		2023		2022

Numerator:
Net income (loss)	$	22,806	$	(46,415	)
Denominator:
Basic weighted average common shares outstanding		52,703,467		37,585,075
Effect of dilutive securities		285,563		—
Diluted weighted-average common shares outstanding		52,989,030

Net income (loss) per share, basic	$	0.43	$	(1.23	)
Net income (loss) per share, diluted	$	0.43	$	(1.23	)

The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net income (loss) per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect:


	Year Ended December 31,
		2023	2022
Options to purchase common stock		3,485,373	3,979,099
Unvested RSUs and PSUs		3,462,595	1,300,397
Total		6,947,968	5,279,496