Business Segments We manage, operate and provide our products and services in four business segments: Market Services, Corporate Services, Information Services and Market Technology. See Note 1, Organization and Nature of Operations, for further discussion of our reportable segments. Our management allocates resources, assesses performance and manages these businesses as four separate segments. We evaluate the performance of our segments based on several factors, of which the primary financial measure is operating income. Results of individual businesses are presented based on our management accounting practices and structure. The following table presents certain information regarding our business segments for the three months ended March 31, 2019 and 2018 : Market Services Corporate Services Information Services Market Technology Corporate Items Consolidated (in millions) Three Months Ended March 31, 2019 Total revenues $ 638 $ 131 $ 193 $ 77 $  $ 1,039 Transaction-based expenses (405 )     (405 ) Revenues less transaction-based expenses 233 131 193 77  634 Operating income (loss) $ 135 $ 46 $ 124 $ 7 $ (37 ) $ 275 Three Months Ended March 31, 2018 Total revenues $ 735 $ 132 $ 174 $ 60 $ 50 $ 1,151 Transaction-based expenses (485 )     (485 ) Revenues less transaction-based expenses 250 132 174 60 50 666 Operating income (loss) $ 147 $ 43 $ 113 $ 2 $ (32 ) $ 273 Certain amounts are allocated to corporate items in our management reports as we believe they do not contribute to a meaningful evaluation of a particular segment's ongoing operating performance. These items include the following: Amortization expense of acquired intangible assets: We amortize intangible assets acquired in connection with various acquisitions. Intangible asset amortization expense can vary from period to period due to episodic acquisitions completed, rather than from our ongoing business operations. As such, if intangible asset amortization is included in performance measures, it is more difficult to assess the day-to-day operating performance of the segments, and the relative operating performance of the segments between periods. Management does not consider intangible asset amortization expense for the purpose of evaluating the performance of our segments or their managers or when making decisions to allocate resources. Therefore, we believe performance measures excluding intangible asset amortization expense provide management with a more useful representation of our segments' ongoing activity in each period. Merger and strategic initiatives expense: We have pursued various strategic initiatives and completed acquisitions and divestitures in recent years which have resulted in expenses which would not have otherwise been incurred. These expenses generally include integration costs, as well as legal, due diligence and other third party transaction costs. The frequency and the amount of such expenses vary significantly based on the size, timing and complexity of the transaction. 2018 Divestiture: We have included in corporate items the revenues and expenses of the Public Relations Solutions and Digital Media Services businesses which were part of the Corporate Solutions business within our Corporate Services segment as these businesses were sold in April 2018. See 2018 Divestiture, of Note 5, Acquisitions and Divestitures, for further discussion. Accordingly, we do not allocate these costs for purposes of disclosing segment results because they do not contribute to a meaningful evaluation of a particular segments ongoing operating performance. * * * * * * A summary of our corporate items is as follows: Three Months Ended March 31, 2019 2018 (in millions) Revenues - divested businesses $  $ 50 Expenses: Amortization expense of acquired intangible assets 26 28 Merger and strategic initiatives expense 9 10 Expenses - divested businesses  42 Other 2 2 Total expenses 37 82 Operating loss $ (37 ) $ (32 )