** Shares of crypto exchange Coinbase COIN.O falls 8.89% to $153.63
** BTIG cuts price target on COIN to $340 from $420; New PT still reflects a 101.6% upside to the stock's last close
** Cites recent softness in COIN's trading volume based on third-party data
** Separately, cryptocurrency and blockchain‑related companies fall after bitcoin drops below the $70,000 level
** The stock price pressure has been mainly driven by expectations for 4Q weakness in transaction volume relative to 3Q and the broader market, brokerage says
** 25 of 37 brokerages rate the stock "buy" or higher, 11 "hold" and 1 "strong sell"; their median PT is $328
** Including session moves, stock is up 43.5% in the last 12 months
(Reporting by Pragyan Kalita in Bengaluru)
((Pragyan.Kalita@thomsonreuters.com))