Jump The Gun Meaning

(idiomatic, finance, investing) To trade securities based on information that is not yet public; to trade on inside information.

Example: 1961 Feb 24, "Sport: Higher & Farther," Time:
  Unperturbed when an overanxious opponent jumped the gun in the women's 60-yd. dash, willowy Wilma Rudolph exploded perfectly from the starting blocks.
1934 May 14, "Theatre: Pulitzer Pother," Time:
  Taking advantage of advance press releases, gabby Walter Winchell jumped the gun a full two weeks by announcing in his radio period and tabloid column that the 1933-34 prizewinner was Men in White by Sidney Kingsley.
2006 May 15, Rob Hughes, "Uneasiness in Italy as Scandal Widens," New York Times (retrieved 3 Sept. 2011):
  The former prime minister appears to be jumping the gun, pre-empting the legal process that is just beginning to dig deeper.