The idiom

Idiom

Idiom is an expression, word, or phrase that has a figurative meaning that is comprehended in regard to a common use of that expression that is separate from the literal meaning or definition of the words of which it is made...

 Jump the gun has its roots in an athlete starting a race before the starting pistol

Starting pistol

A starting pistol or starter pistol is a handgun or electronic toy weapon that is fired to start track and field races, as well as competitive swimming races at some meets. The loud report of the gun going off is a signal to the athletes to begin the event. Usually a cloud of smoke can be seen...

 is fired. It refers to someone or refers to an act when it is started earlier than expected or when something is spoken without required thinking. In finance

Finance

"Finance" is often defined simply as the management of money or “funds” management Modern finance, however, is a family of business activity that includes the origination, marketing, and management of cash and money surrogates through a variety of capital accounts, instruments, and markets created...

it refers to a scenario where various financial instruments are traded based on some knowledge that is not yet public.