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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?

Laurel
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Oli
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    Never heard this. Can you link to an example? – DJClayworth Aug 30 '17 at 16:14
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    @DJClayworth Here's a Reddit post where someone makes the same observation. – Laurel Aug 30 '17 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 Aug 30 '17 at 16:26
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    Reddit commenters may be correct. The industry is such that one influential person at one bank might have used it in one meeting, and it spread across the world within 24 hours... – Oli Aug 30 '17 at 16:35
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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 Aug 30 '17 at 16:54
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    Interesting question. The usage is definitely common in finance, especially among trades when quoting a price: https://forums.babypips.com/t/traders-saying-spot-vs-point/54974 - https://forum.wordreference.com/threads/number-4-7-pronunciation.2325471/ -"Most floor trader jargon developed to prevent confusion that could cost money, and I assume this is another example." –  Aug 30 '17 at 17:47
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    odd -- a morphed version of the British "stop" aka "full stop" as name for a period? – Carl Witthoft Aug 30 '17 at 18:25
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    @Josh - So you think the term was developed by spot traders? – Hot Licks Aug 30 '17 at 19:10
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    @HotLicks - don't know, maybe it is an extension of the term spot they used in "spot price". After all, a dot is a spot!! –  Aug 30 '17 at 19:23
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    I suspect y'all are correct, it's a neologism recently invented by folks in the industry. The only thing I could find in the OED that might relate is: "12. In greyhound racing: one hundredth of a second. [Perhaps with reference to one-hundredth of a second being marked by a spot on an analogue stopwatch.] Ex.:

    1977 Daily Mirror 16 Mar. 29/3 His time of 29.47s. was thirteen spots faster than that recorded by Gaily Noble two races later."

     – Mark D Worthen PsyD Aug 30 '17 at 20:52
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    It was in common use at Morgan Guaranty Trust Company (later J. P. Morgan) in the UK during the early/mid 1980s (overheard from working there as a summer job while at university). – TripeHound Sep 04 '17 at 14:10
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    @DJClayworth Are you certain about the origin of "up three points"? 0.03% would be 3 basis points, which would be the basis of the contraction, not "point zero three" directly. – Oli Sep 05 '17 at 11:54
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    This is my guess. A spot is a little point, like a dot. A dot indicates both the punctuation in a sentence, and in math the separation of the integer part from the decimal. I suppose that saying "spot" there is no misunderstanding between the termination of a sentence, and the part of a number. For examples if I am dictating "please tell to buy X at 3 dot 5 then please sell..." it can be interpreted "buy at 3. 5 then please sell..." but instead the intention was "buy at 3.5, then please sell...". – ealy Sep 05 '17 at 13:43

1 Answers1

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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.

Community
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RaceYouAnytime
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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 Sep 07 '17 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. –  Sep 08 '17 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 Sep 09 '17 at 00:21
  • How does this answer why “spot” and not “point” or “decimal” or “dot”? – 2540625 Jul 12 '22 at 20:14