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I've noticed some people who work with non-integers sometimes read out decimal points as "spot".

E.g. "Pi is three spot one four one".

Particularly found in finance, but I've heard non-finance professionals use it too.

It makes perfect sense to me in terms of avoiding mumbling/mishearing, but I'm wondering about the origin and history?

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    Never heard this. Can you link to an example?
    – DJClayworth
    Commented Aug 30, 2017 at 16:14
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    @DJClayworth Here's a Reddit post where someone makes the same observation.
    – Laurel ♦
    Commented Aug 30, 2017 at 16:22
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    At an absolute wild guess it's to avoid confusing with "up three points" (which is itself derived from "point zero three"). But that is just a completely wild guess.
    – DJClayworth
    Commented Aug 30, 2017 at 16:26
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    OED3 does have a number of definitions under sense II: "A mark or dot; something distinguished by this", but none of them are a decimal point. That entry was updated in June 2016, so if you have documented usage with a new definition they might be interested in recording it.
    – Andrew Leach ♦
    Commented Aug 30, 2017 at 16:54
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    Interesting question. The usage is definitely common in finance, especially among trades when quoting a price: forums.babypips.com/t/traders-saying-spot-vs-point/54974 - forum.wordreference.com/threads/… -"Most floor trader jargon developed to prevent confusion that could cost money, and I assume this is another example."
    – user66974
    Commented Aug 30, 2017 at 17:47

1 Answer 1

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+100

The origin seems to lie in a switch from fraction-based pricing on financial trading markets to decimal-based pricing that took place after a U.S. government mandate in 2000.

The story is explained well in an article titled "Traders learning decimal jargon" syndicated by the Associated Press in 2000. The article starts with an interesting anecdote:

Transactions were proceeding smoothly until one trader increased his offer for 1,000 shares of Hughes Electronics with a shouted phrase. "A teenie!"

For the briefest moment, there almost was quiet in this one corner of the trading floor.

Then McDevitt responded. "You mean teenie or a cent?"

"I apologize. I meant a penny," the trader replied.

The article goes on to explain:

A teenie is trader jargon for 1/16 of a dollar. Hughes, like 100 other companies on the exchange, recently began trading in decimals with one-penny increments.

As the piece elaborates, traders had historically traded in "halves, quarters, eighths, and more recently, 16ths," and had developed their finance jargon around these fractions to simplify their language. When the market moved from speaking in fractions to decimals, their language had to evolve.

Some traders have taken to use the word "spot" to make clear they're talking in decimals, saying "35-spot-4," for example, so it's clear they mean 4 cents, not four teenies.

This change to decimal pricing was made in the year 2000, and testimony on the proposed change can be found on the website of the U.S. Securities And Exchange Committee here.

Based on the Associated Press piece in combination with the SEC record, it seems like a safe conclusion that the use of "spot" to refer to decimal points took place or became popular in the finance industry in or very close to the year 2000 to avert confusion related to switching from fraction-based pricing to decimal-based pricing.

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    Well done. I suspected as much, because the kids didn't understand what it meant for Burns Worldwide to go from ⅛ to 52¼, but it was surprisingly hard to track down sources.
    – choster
    Commented Sep 7, 2017 at 14:48
  • Nice finding, the only problem I have is that the use of "spot" in the sense cited above has been in place at least from the '80s. That's from my personal experience. Currency traders, for instance, used it frequently when quoting a price. Now trading is computer based so I guess it is less commonly used.
    – user66974
    Commented Sep 8, 2017 at 15:59
  • @Josh Interesting. Unfortunately, I'm having a hard time finding research to address that. If I find something I'll update the answer.
    – RaceYouAnytime
    Commented Sep 9, 2017 at 0:21
  • How does this answer why “spot” and not “point” or “decimal” or “dot”?
    – 2540625
    Commented Jul 12, 2022 at 20:14

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