Asset manager giants including BlackRock Inc., Fidelity Investments, T. Rowe Price Group and Franklin Resources Inc. are among the firms seeking regulatory permission to deploy the hybrid structure. Some have been waiting for about two years, ever since Vanguard’s  patent expired .But the size of the waitlist — more than six-times the number of firms that were racing for approval to launch Bitcoin funds — suggests huge industry-wide enthusiasm to take up the Vanguard blueprint. Eric Balchunas, senior E ...