Coinbase falls after co says it expects up to $400 mln hit from cyber attack

Shares of cryptocurrency exchange Coinbase Global COIN.O fall 4.3% to $252.37 in early trading

Co says it expects to incur between $180 million and $400 million in costs related to cyber attack

COIN says cyber criminals had stolen account data for "small subset" of its customers

However, COIN says no passwords, private keys or funds were exposed and Coinbase Prime accounts are untouched

Co will not pay $20 million ransom demand it received and says it will reimburse customers who were tricked into paying attackers

COIN says it has set up $20 million reward for information on attackers

Co earlier in the week became first digital asset player to be included in benchmark S&P 500 index .SPX

As of last close, COIN up nearly 6% YTD