Basic net income per common share is calculated by dividing net income by the weighted average number of common shares outstanding during the period. Diluted net income per common share is computed by dividing net income by the weighted average number of common and dilutive common equivalent shares outstanding during the period. The Company’s potentially dilutive common shares are those that result from dilutive common stock options, non-vested stock relating to restricted stock awards, restricted stock units, and deferred stock units, as well as performance shares in years prior to fiscal 2020. Options to purchase shares of common stock as well as unvested restricted stock and performance stock units are considered to be potentially dilutive common shares.

The calculation of weighted average diluted shares outstanding excludes outstanding stock options associated with the right to purchase less than 0.1 million and 0.2 million shares of common stock for the three months ended March 31, 2020 and 2019, respectively, and less than 0.1 million and 0.2 million shares of common stock for the six months ended March 31, 2020 and 2019, respectively, as their inclusion would have had an antidilutive effect on diluted net income per share for those periods.

The following table sets forth the denominator for the computation of basic and diluted net income per share (in thousands):

	Three Months Ended				Six Months Ended
	March 31,				March 31,
	2020		2019		2020		2019
Net income available to common shareholders	$	1,462	$	1,262	$	1,610	$	2,572
Basic weighted average shares outstanding		13,507		13,390		13,474		13,379
Dilutive effect of outstanding stock options, nonvested restricted stock, restricted stock units, deferred stock units and performance shares		244		395		305		437
Diluted weighted average shares outstanding		13,751		13,785		13,779		13,816

The Company’s Board of Directors has authorized the repurchase of up to $25.3 million of the Company’s outstanding common stock. This authorization does not have an expiration date.