Yes it was. Even stipulating your use of the term &quot;front running&quot;†, it&#x27;s not hard to see how. When humans intermediated trades, spreads were denominated in dimes and quarters (and even higher as you go back further in time). Now they&#x27;re pennies.<p>Google &quot;odd eighths scandal&quot; for a good starting point.<p>† <i>&quot;Front running&quot; has a specific technical meaning, which very few people who throw the term around seem to know about: a front-runner violates a fiduciary duty they have to a client, trading against their clients for their own benefit. Market makers and prop trading firms aren&#x27;t generally brokers for other people and don&#x27;t have that duty; they can&#x27;t &quot;front-run&quot; the people they out-trade.<p>Your real estate agent would &quot;front run&quot; you if they knew you wanted to buy a particular house, knew your maximum price, bought the same house for less than that price and then sold it to you at a profit. Same with your stock broker and, say, IBM stock; they have a duty of best execution to you.</i>