James Leonard Smith allegedly helped steal nearly $6 million from investors desperate for financing.
US authorities allege a Canadian-led group made tens of millions of dollars in penny stock scams dating back a decade.
The Nikola founder could face decades in prison for allegedly false, misleading Twitter posts.
Aron Govil allegedly siphoned $7 million from Cemtrex and Telidyne investors for personal use.
Edgar Radjabli is accused of manipulating the securities market for Veritone, among other schemes.
Evan Greebel allegedly drafted bogus consulting agreements to fend off disgruntled hedge fund investors.