Twitter Keeps Missing Its Advertising Targets as Woes Mount

The World Cup has historically been a boon for Twitter, bringing in record traffic and an influx of advertising dollars.

But this time, when the global soccer tournament started on Nov. 20, Twitter’s U.S. ad revenue was running at 80 percent below internal expectations for that week, three people with knowledge of the figures said.

In tandem, Twitter was rapidly cutting its revenue projections. The company previously forecast that it would…