  The pump and dump scheme is a form of market manipulation attack in which
coordinated actors drive up the price of an asset in order to sell at a higher
price. Due in part to a lack of enforcement, these schemes are widespread
within the cryptocurrency marketplace, but the negative impact of these events
on the coins they target is not yet fully understood. Drawing upon a novel
dataset of pump events extracted from Telegram channels, an order of magnitude
larger than the nearest comparable dataset in the literature, we explore the
differing tactics of pumping channels and the long-term impact of pump and dump
schemes across 765 coins. We find that, despite a short-term positive impact in
some cases, the long-term impact of pump and dump schemes on the targeted
assets is negative, amounting to an average 30% relative drop in price a year
after the pump event.
