We mitigate our foreign currency exchange risk principally by (1) establishing local operations in the markets we serve and (2) invoicing customers in the same currency as the source of the costs. The impact of translating expenses incurred in foreign currencies back into U.S. dollars reduces the impact of translating revenue earned in foreign currencies back into U.S. dollars. In addition, British pound and Singapore dollar expenses incurred as a result of our regional headquarters being located in London and Singapore, respectively, have historically acted as partial operational hedges against our translation exposures to British pound and Singapore dollars.
To show the impact foreign currencies have on our results of operations, we present the change in local currency for revenue and operating expenses on a consolidated basis and by operating segment in Management's Discussion and Analysis of Financial Condition and Results of Operations included herein. The change in local currency represents the change assuming no movement in foreign exchange rates from the prior year. On a quarter-over-quarter basis, for the three months ended September 30, 2017, our total revenue increased 14% in U.S. dollars and 13% in local currency, and our operating income increased 66% in U.S. dollars and 65% in local currency. On a year-over-year basis, for the nine months ended September 30, 2017, our total revenue increased 16% in U.S. dollars and 18% in local currency, and our operating income increased 14% in U.S. dollars and 11% in local currency. For additional detail of the impact of foreign exchange rates on our results of operations, see Management's Discussion and Analysis of Financial Condition and Results of Operations included herein.
We enter into forward foreign currency exchange contracts to manage currency risks associated with intercompany lending and cash management practices. As of September 30, 2017, we had forward exchange contracts in effect with a gross notional value of $2.00 billion ($1.41 billion on a net basis) and a net loss of $8.6 million. This net carrying gain is generally offset by a carrying loss in associated intercompany loans.
Disclosure of Limitations
As the information presented above includes only those exposures that exist as of September 30, 2017, it does not consider those exposures or positions which could arise after that date. The information we present has limited predictive value. As a result, the ultimate realized gain or loss with respect to interest rate and foreign currency fluctuations will depend on the exposures that arise during the applicable period, the hedging strategies at the time, and interest and foreign currency rates.
For other risk factors inherent in our business, see Item 1A. Risk Factors in our 2016 Annual Report on Form 10-K.
Item 4. Controls and Procedures
The Company has established disclosure controls and procedures to ensure material information relating to the Company, including its consolidated subsidiaries, is made known to the officers who certify the Company's financial reports and to the other members of senior management and the Board of Directors.
Under the supervision and with the participation of the Company's management, including our Chief Executive Officer and Chief Financial Officer, we conducted an evaluation of the Company's disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934). Based on this evaluation, our Chief Executive Officer and Chief Financial Officer concluded our disclosure controls and procedures were effective as of the end of the period covered by this report. There were no changes in the Company's internal control over financial reporting during the quarter ended September 30, 2017, that have materially affected, or are reasonably likely to materially affect, the Company's internal control over financial reporting.