Congressional rules on trading had their start in 1789 - The Washington Post

Washington Post

Congress has been doing it since 1789

By Kimberly Kindy, Published: June 23

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It was 1789, and state-backed revolutionary war bonds had become virtually worthless. Treasury Secretary Alexander Hamilton moved in to shore up the investments.
 
Before word spread, members of Congress secretly scooped up thousands of the bonds from unsuspecting farmers and war veterans, paying pennies on the dollar.
....

In response to the scandal, lawmakers prohibited Hamilton and future Treasury secretaries from buying or selling government bonds while in office.
But members of Congress did not extend the ban to themselves, a pattern that persists to this day.

.... Congressional rules on trading had their start in 1789 - The Washington Post