Bitcoin Cash was just recently added to America's number 1 cryptocurrency trading platform, Coinbase. The move was unannounced and impactful. This caused the price to skyrocket from $1,500 to nearly $4,000 in a matter of days.
Coinbase has a very large customer base and few coins available for trading, any coin would see a significant boost simply by being added. Days leading up to the event, the price of Bitcoin cash curiously began to slowly and steadily rise.
Coinbase suspects possible insider trading and are investigating. Here's a link with a more detailed article of the suspicious circumstances.
http://www.businessinsider.com/coinbase-is-investigating-insider-trading-of-bitcoin-cash-2017-12
I ROCK COIN BASE
WHAT
What? You don't, GB3?
coinbase is where magic happens