Westlake Chemical Corporation reported record quarterly net income of $170.3 million, or $2.54 per diluted share, on net sales of $1,004.2 million for the quarter ended September 30, 2013. This represents an increase in net income of $83.3 million, or $1.24 per diluted share, compared to the quarter ended September 30, 2012 net income of $87.0 million, or $1.30 per diluted share, on net sales of $821.2 million.
Net sales for the third quarter of 2013 increased by $183.0 million compared to net sales for the third quarter of 2012, mainly attributable to higher sales volumes for styrene and caustic, higher sales prices for most of our major products and sales contributed by our specialty PVC pipe business, which we acquired in May 2013.
Styrene sales volumes for the third quarter of 2012 were negatively impacted by a turnaround of the styrene plant in Lake Charles, Louisiana. Income from operations was $266.6 million for the third quarter of 2013 as compared to $142.5 million for the third quarter of 2012. Income from operations for the third quarter of 2013 benefited primarily from improved olefins and vinyls integrated product margins, largely due to higher sales prices for most of our major products and lower overall feedstock costs as compared to the prior year period.
Third quarter 2013 net income of $170.3 million, or $2.54 per diluted share, increased from the net income of $145.8 million, or $2.17 per diluted share, reported in the second quarter of 2013. Third quarter 2013 sales of $1,004.2 million increased by $65.2 million compared to sales of $939.0 million in the second quarter of 2013.
The increase in sales was largely due to higher sales volumes of polyethylene. Third quarter 2013 income from operations of $266.6 million increased by $31.4 million over the income from operations in the second quarter of 2013 of $235.2 million. This increase in income from operations was primarily attributable to lower feedstock costs and higher polyethylene sales volumes as compared to the second quarter of 2013.
For the nine months ended September 30, 2013, net income was $439.5 million, or $6.54 per diluted share, on net sales of $2,807.9 million. This represents an increase in net income of $149.2 million, or $2.21 per diluted share, from the nine months ended September 30, 2012 net income of $290.3 million, or $4.33 per diluted share, on net sales of $2,770.0 million.
Net sales for the nine months ended September 30, 2013 increased by $37.9 million compared to the prior year period mainly due to higher sales volumes and sales prices for styrene, PVC resin and caustic, higher polyethylene sales prices and sales contributed by our specialty PVC pipe business, mostly offset by lower feedstock, ethylene and ethylene co-products sales volumes.
Income from operations was $695.9 million for the nine months ended September 30, 2013 as compared to $459.1 million for the nine months ended September 30, 2012. The increase in income from operations was primarily attributable to higher olefins and vinyls integrated product margins, predominantly due to a significant decrease in feedstock costs as industry ethane prices decreased 40.4% and industry propane prices decreased 10.1% in the nine months ended September 30, 2013 as compared to the nine months ended September 30, 2012.
