(13) Loss Per Share

Basic loss per common share is calculated based on the weighted average number of common shares outstanding during the three months ended September 30, 2013 and 2012, respectively. Diluted loss per common share assumes the exercise of stock options or the vesting of restricted stock grants provided in each case the effect is dilutive.

The reconciliation of the amounts used to compute basic and diluted loss per common share for the three months ended September 30, 2013 and 2012 is as follows:

		Three Months Ended
		September 30,
		2013	2012
Basic loss per share computation
Numerator:
Net loss attributable to Globe Specialty Metals, Inc.	$	(6,852)	(5,705)
Denominator:
Weighted average basic shares outstanding		75,310,143	75,050,560
Basic loss per common share	$	(0.09)	(0.08)
Diluted loss per share computation
Numerator:
Net loss attributable to Globe Specialty Metals, Inc.	$	(6,852)	(5,705)
Denominator:
Weighted average basic shares outstanding		75,310,143	75,050,560
Effect of dilutive securities		—	—
Weighted average diluted shares outstanding		75,310,143	75,050,560
Diluted loss per common share	$	(0.09)	(0.08)

Potential common shares associated with outstanding stock options totaling 227,874 and 208,578 were excluded from the calculation of diluted loss per common share because their effect would be anti-dilutive for the three months ended September 30, 2013 and 2012, respectively.