** Shares of U.S. cryptocurrency and blockchain-related companies decline premarket, tracking losses in bitcoin BTC=
** Democratic candidate Kamala Harris put her Republican rival Donald Trump on the defensive in a combative presidential debate on Tuesday
** The former U.S. president has projected himself as the pro-bitcoin candidate ahead of the election in November
** Speaking at the Bitcoin 2024 convention in Nashville in July, Trump had positioned himself as the pro-cryptocurrency candidate
** His return could be a huge win for the industry, which has often complained of excessive oversight and a hostile regulatory environment under President Joe Biden
** Bitcoin, the world's biggest cryptocurrency down 1.9%, while Ether ETH= falls 2%
** Crypto exchange Coinbase Global COIN.O falls 2.7%, while Blockchain farm operator Bitfarms Ltd BITF.O down 2% before the bell
** Crypto miners: Riot Platforms Inc RIOT.O Marathon Digital MARA.O, and U.S.-listed shares of Hut 8 HUT.O down 2.6%-4.1% premarket
** Software firm and BTC buyer MicroStrategy MSTR.O declines 3.8% premarket
** BTC down ~16% over the past three months, but has gained ~35% YTD
(Reporting by Manya Saini in Bengaluru)