Basic (loss) income per share is computed by dividing net (loss) income by the weighted average number of common shares outstanding during the period. Diluted (loss) income per share assumes the issuance of potentially dilutive shares of common stock during the period. The following table reconciles the numerators and denominators of the basic and diluted (loss) income per share computations:

For the three and nine months ended September 30, 2017, 0.7 million and 0.6 million of stock options were not included in the calculation because they would have an anti-dilutive effect, compared to less than 0.1 million for the same prior year periods.