Table:
| ($ in millions) |  |  |  |
| --- | --- | --- | --- |
| For the fourth quarter: | 2019 | 2018 | Yr.-to-Yr. Percent/ Margin Change* |
| Total consolidated expense and other (income) | $7,107 | $6,253 | 13.7% |
| Non-operating adjustments |  |  |  |
| Amortization of acquired intangible assets | (294) | (106) | 176.0 |
| Acquisition-related charges | (27) | (13) | 104.7 |
| Non-operating retirement related (costs)/income | (196) | (387) | (49.4) |
| Operating (non-GAAP) expense and other (income) | $6,591 | $5,746 | 14.7% |
| Total consolidated expense-to-revenue ratio | 32.6% | 28.7% | 3.9pts |
| Operating (non-GAAP) expense-to-revenue ratio | 30.3% | 26.4% | 3.9pts |
Paragraphs:
* 2019 results were impacted by Red Hat purchase accounting and acquisition-related activity.
Total expense and other (income) increased 13.7 percent in the fourth quarter with an expense-to-revenue ratio of 32.6 percent compared to 28.7 percent in the fourth quarter of 2018. The year-to-year increase was a result of higher spending (15 points) driven by Red Hat (15 points) and higher acquisitionrelated charges and amortization of acquired intangible assets associated with the Red Hat transaction (4 points), partially offset by higher divestiture gains (3 points) and lower non-operating retirement-related costs (3 points).
Total operating (non-GAAP) expense and other income increased 14.7 percent year to year primarily driven by the higher spending, partially offset by the divestiture gains, as described above.
Question:
What caused total operating (non-GAAP) expense and other income to increase?
Answer: driven by the higher spending, partially offset by the divestiture gains, as described above.