Fourth, we are setting the new paradigm in the sector, working in several areas including commercial approach, devices and networks that will show progress [ph] later on. Let me say that we continue to invest for future growth, with focused investments in mobile broadband and fiber, where the quantum leap in terms of coverage is particularly remarkable.
Finally, on the financial front, we have been productive year-to-date, with 2012 maturities already being fully refinanced, more than 40% of 2013 maturities refinanced and the Colombian restructuring executed. And that we are taking further actions to progressively reduce the leverage ratio and to protect the rating.
Please turn now to Slide #4 for a review of first quarter financial performance. Revenue reached over EUR 15.5 billion in the first quarter, up 0.5% year-on-year, despite the adverse conditions faced in most of our European markets. Excluding MTR cuts, revenue growth was 1.6%. Below the revenue line, both in 2011 and 2012, we have booked several material exceptional items. In particular, 2012 accounts include a noncash impact of the reduction in the value of our investments in Telecom Italia, with a negative effect in net income of EUR 637 million, while a year ago, we recorded a positive impact from the reduction in our stake in BT.
So to better understand the underlying performance of the company, we will focus on the P&L excluding those nonrecurring effects. As such, underlying OIBDA was close to EUR 5.1 billion, down 7.4% year-on-year, while underlying net income totaled almost EUR 1.3 billion. CapEx to sales was 11%, higher than a year ago, though below our 2012 target due to different quarterly execution path along the year. Finally, let me highlight that the first quarter results are in line with our internal expectations and therefore, we would reiterate our 2012 guidance.