Donald Trump has nominated billionaire and Army veteran Vincent Viola to be the secretary of the Army. Viola is a retired Army major and graduate of West Point who is worth nearly $2 billion. He’s the founder of a high-frequency trading company called Virtu. High-frequency trading is a process in which financial firms use algorithms to execute rapid-fire trades, at a speed of a half-millionth of a second, in order to generate tiny profits on each transaction that add up to massive sums of money. Critics have warned the scheme threatens the stability of global financial markets. Viola is also the owner of the National Hockey League’s the Florida Panthers.