18. NET INCOME (LOSS) PER SHARE

        Basic income (loss) per share excludes dilution and is computed by dividing net income (loss) attributable to Huntsman Corporation common stockholders by the weighted average number of shares outstanding during the period. Diluted loss per share reflects potential dilution and is computed by dividing net income available to common stockholders by the weighted average number of shares outstanding during the period, increased by the number of additional shares that would have been outstanding if the potential dilutive units had been exercised or converted.

        Basic and diluted income (loss) per share is determined using the following information (in millions):

        Additional stock-based awards of 6.8 million and 6.9 million weighted average equivalent shares of stock were outstanding during the three months ended September 30, 2011 and 2010, respectively, and additional stock-based awards of 6.7 million and 7.1 million weighted average equivalent shares of stock were outstanding during the nine months ended September 30, 2011 and 2010, respectively. These stock-based awards were not included in the computation of diluted earnings per share for the three and nine months ended September 30, 2011 and 2010 periods because the effect would be anti-dilutive. In addition, our 7% convertible notes due 2018 would have had a weighted average effect of 1.2 million shares of common stock for the nine months ended September 30, 2010 and interest expense, net of tax, of $1 million would have been included as an adjustment to the numerator of the diluted loss per share calculation for the nine months ended September 30, 2010. However, the potential effect of assumed conversion of the convertible notes due 2018 were not included in the computation of diluted earnings per share for the nine months ended September 30, 2010 because the effect would be anti-dilutive.