Something strange has been happening to several of ARK’s ETFs recently: Assets have been spiking like blood sugar after a pumpkin spice latte. There has been speculation about the causes, but no one, other than the unidentified traders, knows why. One explanation is that the activity is merely heartbeat trades that were used to wash taxes. Another is that a zealous bunch of retail investors wanted exposure to a few IPOs. But the most interesting theory, from the Financial Times’ Robin Wigglesworth, is tha ...