Table:
| ($ in millions) |  |  |  |
| --- | --- | --- | --- |
| For the year ended December 31: | 2019 | 2018 | Yr.-to-Yr. Percent/ Margin Change* |
| Total consolidated expense and other (income) | $26,322 | $25,594 | 2.8% |
| Non-operating adjustments |  |  |  |
| Amortization of acquired intangible assets | (764) | (437) | 74.8 |
| Acquisition-related charges | (409) | (16) | NM |
| Non-operating retirement related (costs)/income | (615) | (1,572) | (60.9) |
| Operating (non-GAAP) expense and other (income) | $24,533 | $23,569 | 4.1% |
| Total consolidated expense-to-revenue ratio | 34.1% | 32.2% | 2.0 pts. |
| Operating (non-GAAP) expense-to-revenue ratio | 31.8% | 29.6% | 2.2 pts. |
Paragraphs:
Total Expense and Other (Income)
* 2019 results were impacted by Red Hat purchase accounting and acquisition-related activity.
The following Red Hat-related expenses were included in 2019 total consolidated expense and other (income), with no corresponding expense in the prior-year: Red Hat operational spending, interest expense from debt issuances to fund the acquisition and other acquisition-related activity, including: amortization of acquired intangible assets, retention and legal and advisory fees associated with the transaction.
Total expense and other (income) increased 2.8 percent in 2019 versus the prior year primarily driven by higher spending including Red Hat operational spending and investments in software and systems innovation, higher interest expense, non-operating acquisition-related activity associated with the Red Hat transaction and lower IP income, partially offset by lower non-operating retirement-related costs, divesture-related activity (gains on divestitures and lower spending) and the effects of currency. Total operating (non-GAAP) expense and other (income) increased 4.1 percent year to year, driven primarily by the factors above excluding the higher non-operating acquisition related activity and lower non-operating retirement-related costs described above.
Question:
What caused the increase in the total operating expenses?
Answer: Total operating (non-GAAP) expense and other (income) increased 4.1 percent year to year, driven primarily by the factors above excluding the higher non-operating acquisition related activity and lower non-operating retirement-related costs described above.