For us, this reduced GAAP earnings in Q4 by $63 million.
We've received one $1.7 billion in cash under our hedge contracts since their inception more than five years ago.
For the fourth quarter, sales were $3.3 billion, up 11% sequentially, and 17% year over year.
Our operating margin expanded 500 basis points year over year to 19.4%.
Operating income grew 18% sequentially and 58% year over year.
EPS of $0.52 cents was up 21% sequentially and 13% year over year.
We generated $464 million of free cash flow in the fourth quarter, $948 million for the full year, and we finished the year with $2.7 billion in cash on our balance sheet.
Our sales were down 12% in the first half as most economies were impacted by pandemic-related lockdowns.
But in the second half, we improved sales 24% over the first, while growing operating income, 122%, returning to year-over-year growth and generating very strong free cash flow.
For the year, we generated almost $1 billion of free cash flow and our balance sheet remains very strong.
At the top were specialty materials with sales up 20% year over year, and environmental technologies up 19% year over year, both significantly outperforming their end markets.
In the range of $100 per car in Corning content, we're collaborating with more OEMs and we're offering more solutions to help move the industry forward.
And we continue to see strong adoption of our technology by auto OEMs. Our recent proof point is the new Mercedes-Benz Hyperscreen dashboard display, which features a Gorilla Glass cover nearly 5 feet wide.
We're well on our way to building a $0.5 billion business.
Soon after, we were awarded $204 million in funding from the U.S. government to substantially expand domestic manufacturing capacity for Valor vials.
We produce millions of Valor vials and shipped enough for more than 100 million doses, supporting multiple vaccine developers.
We received $15 million from the U.S. government to expand domestic capacity for robotic pipette tips which are used for COVID diagnostic testing.
I noted that specialty materials sales were up 20% year over year in Quarter 4.
They were up 18% for the full year in a smartphone market that declined 7%.
Operators can actually save up to $500 per terminal location, dramatically lowering installation cost and speeding up deployment.
75-inch sets were up more than 60% for the full year.
Large TVs are most efficiently made on Gen 10.5 plants.
Corning is well-positioned to capture that growth with its Gen 10.5 plants in China including the two newest Gen 10.5 facilities in Wuhan and Guangzhou, which are now expanding production to meet customer demand.
In the fourth quarter, we grew sales 11% sequentially and 17% year over year to $3.3 billion, exceeding expectations.
Excluding the consolidation of Hemlock Semiconductor, sales grew 11% year over year, with every segment growing sales and net income.
Specialty materials and environmental technologies deli -- delivered particularly strong year-over-year sales growth, up 20% and 19%, respectively, both outperforming their underlying markets.
Our operating margin was 19.4%.
That is an improvement of 500 basis points on a year-over-year basis.
We grew operating income 18% sequentially and 58% year over year.
EPS of $0.52 was up 21% sequentially and 13% year over year.
We generated $464 million of free cash flow in the quarter.
Cumulative free cash flow for the full year was $948 million.
We ended the year with a cash balance of $2.7 billion.
In display technologies, fourth-quarter sales were $841 million, up 2% sequentially and 6% year over year.
And net income was $217 million, up 11% sequentially and 21% year over year.
Display's full-year sales were $3.2 billion, and net income was $717 million.
We remain confident that large-size TVs will continue to grow, and we are well-positioned to capture that growth with Gen 10.5, which is the most efficient gen size for large TV manufacturing.
In optical communications, fourth-quarter sales were $976 million, up 8% year over year and 7% sequentially.
Fourth-quarter core net income of $141 million was up 127% year over year, and 23% sequentially.
In environmental technologies, fourth-quarter sales were $445 million, up 19% year over year and 17% sequentially, ahead of expectations as markets continue to improve and GPF adoptions continued in China.
Net income was $93 million, up 45% year over year and 35% sequentially, driven by strong operational performance globally and successful ramping of additional GPF capacity in China.
For the full year, sales were $1.4 billion and our performance was better than the underlying market.
Net income was $197 million.
We are ahead of our original timeframe to build a $500 million GPF business.
Q4 sales of $545 million were up 20% year over year, full-year sales were $1.9 billion, up 18% year over year, despite a 7% decline in the smartphone market, driven by strong demand for our premium cover materials and our other innovations.
Net income was $423 million, up 40% from 2019 on higher sales volume and strong cost performance.
Life sciences fourth-quarter sales were $274 million, up 7% year over year and 23% sequentially, driven by strong demand for COVID-related products, including bioproduction products used in clinical trials.
Net income was $42 million, up 11% year over year and 50% sequentially.
We strengthened our balance sheet, established growth in the second half, and generated a free cash flow of $948 million for the year.
As we look ahead, we have strong momentum coming into 2021 and expect year-over-year growth to accelerate in the first quarter.
Specifically, we expect core sales of $3.0 billion to $3.2 billion, compared to $2.5 billion in the first quarter last year, and earnings per share of $0.40 to $0.44, which is double last year's first-quarter earnings per share at the low end of the range.

Summary:
For the fourth quarter, sales were $3.3 billion, up 11% sequentially, and 17% year over year.
EPS of $0.52 cents was up 21% sequentially and 13% year over year.
In the fourth quarter, we grew sales 11% sequentially and 17% year over year to $3.3 billion, exceeding expectations.
EPS of $0.52 was up 21% sequentially and 13% year over year.
In display technologies, fourth-quarter sales were $841 million, up 2% sequentially and 6% year over year.
In optical communications, fourth-quarter sales were $976 million, up 8% year over year and 7% sequentially.
As we look ahead, we have strong momentum coming into 2021 and expect year-over-year growth to accelerate in the first quarter.
Specifically, we expect core sales of $3.0 billion to $3.2 billion, compared to $2.5 billion in the first quarter last year, and earnings per share of $0.40 to $0.44, which is double last year's first-quarter earnings per share at the low end of the range.