6. Net Income per Share

The following table presents the calculation of basic and diluted net income per share (in thousands, except per share information):

	Three Months Ended
	March 31,
	2018		2017
Net income	$	4,928	$	2,709
Basic:
Weighted-average shares of common stock outstanding		32,752		33,383
Shares used in computing basic net income per share		32,752		33,383
Effect of dilutive securities:
Restricted stock subject to vesting		491		402
Shares issuable for acquisition consideration (1)		547		509
Shares used in computing diluted net income per share		33,790		34,294

Basic net income per share	$	0.15	$	0.08
Diluted net income per share	$	0.15	$	0.08

Anti-dilutive restricted stock not included in the calculation of diluted net income per share		120		122

(1)

For the three months ended March 31, 2018, this represents the shares held in escrow pursuant to: (i) the Asset Purchase Agreement with BioPharm Systems, Inc. ("BioPharm"); (ii) the Asset Purchase Agreement with Zeon Solutions Incorporated and certain related entities (collectively, "Zeon"); (iii) the Asset Purchase Agreement with RAS & Associates, LLC ("RAS"); and (iv) the Asset Purchase Agreement with Clarity Consulting, Inc. and Truth Labs, LLC (together, "Clarity"), as part of the consideration. For the three months ended March 31, 2017, this represents the shares held in escrow pursuant to: (i) the Asset Purchase Agreement with BioPharm; (ii) the Asset Purchase Agreement with Zeon; (iii) the Asset Purchase Agreement with The Pup Group, Inc. d/b/a Enlighten ("Enlighten"); and (iv) the Asset Purchase Agreement with RAS, as part of the consideration.

Prior to 2018, the Company's Board of Directors authorized the repurchase of up to $135.0 million of Company common stock. On February 20, 2018, the Board of Directors authorized the expansion of the stock repurchase program by authorizing the repurchase of up to an additional $25.0 million of Company common stock for a total repurchase program of $160.0 million and extended the expiration date of the program from December 31, 2018 to December 31, 2019. The program could be suspended or discontinued at any time, based on market, economic, or business conditions. The timing and amount of repurchase transactions will be determined by management based on its evaluation of market conditions, share price, and other factors. Since the program's inception on August 11, 2008, the Company has repurchased approximately $137.1 million (12.5 million shares) of outstanding common stock through March 31, 2018.