One thing we learned about Twitter this week: its user base is very international and growing more so by the day.
That’s not an inherent problem; it may indeed be an opportunity as most global ad growth is happening outside the U.S.
But this is a problem: Twitter appears to be reaching full penetration in the U.S. The company says it had 49.2 million U.S. users who signed in at least once a month during the second quarter of 2013, up from roughly 48 million in the first quarter. Monthly users had jumped by 3 million over the previous three-month period, and 5 million before that, so growth appears to be slackening.