“What remains unknown-and may never fully be accounted for-is how much money secretive ‘shadow money’ organizations spent, with some investing massive sums on ads, but also on unreported and purportedly ‘non-political’ activities, as the election neared. It may take years to determine how much they spent.”
More: PressTV - US election costs taxpayers $6bn

Why do we have hyphens in the underlined parts?