Table:
| ($ in millions) |  |  |  |
| --- | --- | --- | --- |
| For the year ended December 31: | 2019 | 2018* | Yr.-to-Yr. Percent/ Margin Change |
| Global Business Services |  |  |  |
| External gross profit | $4,606 | $4,448 | 3.5% |
| External gross profit margin | 27.7% | 26.8% | 0.9 pts. |
| Pre-tax income | $1,666 | $1,629 | 2.2% |
| Pre-tax margin | 9.9% | 9.6% | 0.2 pts. |
Paragraphs:
The GBS profit margin increased 0.9 points to 27.7 percent and pre-tax income of $1,666 million increased 2.2 percent year to year. The pre-tax margin of 9.9 percent increased slightly year to year. The year-to-year improvements in margins and pre-tax income were driven by the continued mix shift to higher-value offerings, the yield from delivery productivity improvements and a currency benefit from leveraging the global delivery resource model. We continued to invest in our services offerings and skills necessary to assist our clients on their cloud journey.
* Recast to reflect segment changes.
Question:
What caused the decrease in the pre-tax income in 2019?
Answer: The year-to-year improvements in margins and pre-tax income were driven by the continued mix shift to higher-value offerings, the yield from delivery productivity improvements and a currency benefit from leveraging the global delivery resource model.