Robert Maguire for Open Secrets:

A secretive political group that is little more than a mailbox full of money in a Des Moines UPS Store raised more than $29.4 million in 2016, most of which was funneled into ads aimed at electing Republicans.

Tax documents obtained by the Center for Responsive Politics show that American Future Fund (AFF), a 501(c)(4) social welfare organization that doesn’t have to disclose its donors, had a banner year in 2016.

The $29.4 million haul marks the group’s highest revenues since it was cut from the constellation of political organizations linked to billionaire industrialists Charles and David Koch amidst a campaign money laundering scandal in 2012. In 2015, the dark money group raised just a little over $350,000.

Bringing in such a considerable sum is no small feat for an organization that boasts no employees nor any measurable social welfare beyond its robust political spending. But in the world of secretive political groups, it’s not an anomaly.