<h4>Quick Take</h4> <ul> <li>Regulators continue to throw cold water on prospects for an exchange-traded fund tied to bitcoin. </li> <li>But that hasn&#8217;t stopped some firms from exploring funds of their own. </li> <li>BlockForce Capital, Blockchain, and Coinbase are three firms kicking the tires on an ETF tied to crypto, <em>The Block </em>has learned. </li> </ul>