the.com/insider trading

means Buying or selling stock using material nonpublic information not available to other investors — illegal in most markets because it turns the trading floor into a card game where one player can see everyone's hand.

from The pieces are plain English, not borrowed or coined with flair: 'insider' (one who stands inside an organization, access others lack) joined with 'trading' (the ordinary buying and selling of securities). The phrase hardened into its current legal sense mainly in the 20th century, as securities regulators — notably after the U.S. created the SEC in the 1930s — needed a name for the specific wrong of trading on confidential corporate information. No colorful backstory here; the vivid part is entirely in what the act describes, not in the word's birth.