Viola, whom Trump selected Monday for the Army's top post, has a net worth of $2.3 billion, according to Bloomberg. Much of that wealth has come from Virtu Financial (virt, -0.62%), the high-frequency trading firm that Viola, 60, founded in 2008 and took public last year: Viola still owns nearly 58% of Virtu, according to the company, which has a market cap of about $2.2 billion.

Indeed, as Virtu filed for an initial public offering in March 2014, The Wall Street Journal declared that Viola was set to become the high-frequency trading industry's very first billionaire upon the IPO.

But there was a problem: It was a terrible time to be a high-frequency trading billionaire.