As the site’s audience approaches the saturation point in many advanced countries—more than sixty per cent in the U.S. and the U.K.; more than eighty-five per cent in Chile, Turkey, and Venezuela—its rate of expansion is inevitably slowing down. Between March, 2009, and March, 2010, the number of monthly active users rose a hundred and fifty-four per cent. Between March, 2011, and March, 2012, the growth rate was forty-one per cent. Quarterly figures confirm the slowdown. In the first quarter of 2010, the growth rate was 26.5 per cent. In the first quarter of this year, it was 8.9 per cent.

Another disturbing sign—and one very familiar to students of the dot-com bubble—is that Facebook’s costs are rising considerably faster than its revenues. Between the first quarter of 2011 and the first quarter of 2012, as it hired more engineers and sales people, and continued to invest in the site, its costs shot up ninety-seven per cent. Revenues rose by forty-five per cent. Consequently, Facebook’s profits in the three months to March were actually lower than they were a year earlier: two hundred and five million dollars compared to two hundred and thirty-three million.