What's a more common term for "penny jumping"?

Question

In securities trading, we have a particular term which I think has broader applicability, so I'm seeking a more common (or at least more universally comprehensible) term for it, that I can use in casual conversation (outside the industry).

The term is penny-jumping, and applied literally, means "taking advantage of the knowledge that someone else's order will move the market, by placing a similar order at a trivially improved price ahead of his", thus "riding his wave" to your benefit and his expense.

But we apply it more liberally than that: it essentially means a kind of obnoxious parasitism¹, and apply it to a variety of situations.

More common example:

Imagine standing on the curb for 15 minutes trying to hail a cab, only to have another person jump in front of you (by a few feet or a single block), and flag "your" cab down at the last minute. While you've waited for 15 minutes, they've only had to wait a few seconds, and they were able to benefit (to your detriment) by making only a trivial "improvement" over your "bid" (those few feet they stepped out in front of you).

Of course, the analogy isn't perfect, but analogies rarely are, and that's how we use it.

Another term of art for this, in the industry, is front-running (though the nuances are different and front-running more explicitly refers to the illegal practice) , though I think penny-jumping captures the same idea more descriptively: the parasite jumps ahead of you for a cost which is trivial to him (a penny), thereby capturing an outsized reward at your expense.

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¹ If done using non-public information, particularly information derived from a privileged relationship with a client (to whom you owe a fiduciary duty), penny-jumping is illegal and is usually termed "front-running" (which is the name of the crime, historically committed by brokers who intermediate between clients and markets). But I'm not concerned with this sense of the word; I'm seeking something which is sleazy and obnoxious, not illegal or fraudulent: think "parasite", not "criminal".

Answer 1

Gazump has the definitions:

gazump

(UK) To swindle; to extort.

(UK, Australia, real estate) To raise the selling price of something (especially property) after previously agreeing to a lower one.

(UK, Australia, real estate) To buy a property by bidding more than the price of an existing, accepted offer.

(UK, Australia) To trump or preempt; to reap the benefit underhandedly from a situation that someone else has worked to create.
[Wiktionary]

The fourth listed certainly corresponds to OP's request, but I'd say that the third is by far the commonest usage.

Here are some non-house-buying examples from the internet:

Offered what was asked but got gazumped:

'I Offered an ebay seller what he stated on the ad , but then find out he has sold it to someone else, which means this was an auction not a classified add, I wasted my time' [sic]

.........

United gazumped by City in race for £18m midfielder

.........

It Looks Like The Pharmacists Have Just Gazumped the Docs.