Twitter's growth in the US grinds to a halt

Twitter failed to add new users in the U.S, according to its latest earnings report.

It's bad news for a company whose U.S. market is its largest driver of revenue.

In its second quarter financial earnings statement, the social network had 65 million monthly active U.S. users - the exact same amount as last quarter.

Even if you add in its SMS users - those who access the service via text message - the growth remains stalled at 66 million monthly active users.

It's a problem given that those users also make up Twitter's largest revenue source. The company made $286 million in U.S.-based advertising revenue, or 63 percent of its revenue overall.

Twitter has shown that it can make money off its U.S. users, but it's going to be hard for the company to show Wall Street that it can survive if it's not growing its most lucrative user base simultaneously.

Here's the bad news in chart form: