Growth momentum was sustained, and we delivered a fifth consecutive quarter of margin expansion, achieving the highest pre-tax operating margin since 2015 and cash flow from operations in excess of $1 billion.
Second, internationally, we recorded growth in all three areas, with revenue up 11% year-on-year, consistent with our ambition of double-digit revenue growth compared to the second half of 2020.
And while we are in the early innings, we are excited about the prospect of transitioning the majority of our software customer base, of over 1,700 companies, to our digital platform during the next few years.
The market fundamentals have improved steadily throughout 2021, especially over the last few weeks, with oil and gas prices attaining recent highs, inventories at their lowest levels in recent history, a rebound in demand and encouraging trends in the pandemic containment efforts.
Year-to-date revenue growth in Latin America is at 30%, with broad activity growth across multiple countries, including Argentina, Brazil, Ecuador and Guyana.
Directionally, we anticipate another quarter of growth, with an ambition for growth across all divisions.
Growth will be led by Production Systems and Digital & Integration, benefiting from a year-end sales uplift, tempered by typical seasonality in Reservoir Performance and Well Construction.
With this fourth quarter outlook, we expect to reach our double-digit international growth ambition for the second half of 2021, when compared to the second half of 2020.
Consequently, on a full year basis, we remain confident in attaining the high end of our guidance of 250 bps to 300 bps EBITDA margin expansion, an excellent foundation for expansion in the year ahead.
In North America, we anticipate capital spending growth to increase around 20%, impacting both the onshore and offshore markets.
In North America, we have enhanced our market positioning and are now biased to accretive growth onshore and will benefit from strong growth offshore in the Gulf of Mexico.
Consequently, we expect margins to expand further in 2022, supporting material earnings growth potential and are increasingly confident in achieving our mid-cycle adjusted EBITDA margin ambition of 25% or higher and sustaining a double-digit free cash flow margin throughout the cycle.
Third quarter earnings per share, excluding charges and credits, was $0.36.
This represents an increase of $0.06 compared to the second quarter of this year and an increase of $0.20 when compared to the same period of last year.
In addition, we recorded in the third quarter a $0.03 gain relating to a start-up company we had previously invested in.
Overall, our third quarter revenue of $5.8 billion dollars increased 4% sequentially.
Pretax operating margins improved 120 basis points to 15.5% and have now increased five quarters in a row.
Companywide adjusted EBITDA margin of 22.2% in the quarter increased 90 basis points sequentially.
Third quarter Digital & Integration revenue of $812 million was essentially flat sequentially as lower sales of digital solutions were offset by higher APS revenue.
Pretax operating margins increased 154 basis points to 35%, largely as a result of improved commodity pricing in our Canada APS project.
Reservoir Performance revenue of $1.2 billion increased 7% sequentially.
Margins expanded 202 basis points to 16%, largely due to higher offshore and exploration activity, as well as accelerated new technology adoption.
Well Construction revenue of $2.3 billion increased 8% sequentially due to higher land and offshore drilling, both internationally and in North America.
Margins increased 230 basis points to 15.2% due to the higher drilling activity and a favorable geographical mix.
Finally, Production Systems revenue of $1.7 billion was essentially flat sequentially while margins decreased 27 basis points to 9.9%.
Cash flow from operations was once again strong as we generated $1.1 billion of cash flow from operations and free cash flow of $671 million during the quarter.
This represented a significant sequential increase when adjusting for last quarter's exceptional tax refund of $477 million.
We paid $42 million of severance during the quarter.
As a result of this strong cash flow performance, net debt decreased sequentially by $588 million to $12.5 billion.
During the quarter, we made capital investments of $399 million.
For the full year 2021, we are now expecting to spend approximately $1.6 billion on capital investments.
In total, during the first nine months of the year, we have generated over $2.7 billion of cash flow from operations and $1.7 billion of free cash flow.
This is evidenced by the fact that gross debt has decreased by almost $1.5 billion since the beginning of the year.
Net debt has reduced by $1.4 billion during this same period.

Summary:
The market fundamentals have improved steadily throughout 2021, especially over the last few weeks, with oil and gas prices attaining recent highs, inventories at their lowest levels in recent history, a rebound in demand and encouraging trends in the pandemic containment efforts.
Year-to-date revenue growth in Latin America is at 30%, with broad activity growth across multiple countries, including Argentina, Brazil, Ecuador and Guyana.
Directionally, we anticipate another quarter of growth, with an ambition for growth across all divisions.
Growth will be led by Production Systems and Digital & Integration, benefiting from a year-end sales uplift, tempered by typical seasonality in Reservoir Performance and Well Construction.
With this fourth quarter outlook, we expect to reach our double-digit international growth ambition for the second half of 2021, when compared to the second half of 2020.
In North America, we have enhanced our market positioning and are now biased to accretive growth onshore and will benefit from strong growth offshore in the Gulf of Mexico.
Third quarter earnings per share, excluding charges and credits, was $0.36.
Overall, our third quarter revenue of $5.8 billion dollars increased 4% sequentially.
Pretax operating margins improved 120 basis points to 15.5% and have now increased five quarters in a row.
For the full year 2021, we are now expecting to spend approximately $1.6 billion on capital investments.