In addition, the recent additions of the sales force and our focus on direct advertising relationships are gaining traction. We are uniquely positioned in the market to deliver brand lift, customer leads, e-commerce transactions and customer relationship management offerings and scale. And we are starting to position the company to take a better advantage of our competitive differentiation. Through this end, we are aligning our business to work more closer together. One step in this direction is to consolidate our Mediaplex technology platform business with our Media segment, which we discussed in our prior calls and announced today as part of our Q2 results.
Mediaplex is now beginning to leverage its strategic advertiser relationships and the first-party data to capture incremental display revenue, so it makes sense to push this consolidation forward ahead of the holiday season. Our confidence in the future is reflected in our stock-buyback activity. We purchased 5.9 million shares in Q2, which was more than 7% of the total shares outstanding as of the end of Q1. And during our -- due to our strong cash flow generation and financial flexibility, our board has authorized an additional $100 million in buyback.
Now I'll turn the call over to John Pitstick, who will review Q2 results and our outlook for the second half of the year, and John Giuliani will discuss our progress on our initiatives to drive these businesses forward. John?
John PitstickThanks, Jim. Revenue for Q2 of $161 million was above the high end of our guidance and represented a reported revenue increase of 29% and pro forma growth of 11%. Excluding the impact of the planned O&O revenue decline, which I'll speak to in a moment, the remainder of our businesses posted 19% pro forma growth in Q2. The worldwide growth rate in Affiliate Marketing of 3% was below our guidance for the segment of mid-single-digit growth. FX rates and additional weakness in Europe negatively impacted Affiliate revenue relative to our guidance. The U.S. business continues to perform well and posted high single-digit growth in Q2. Read the rest of this transcript for free on seekingalpha.com