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Comment by z_zetetic_z | Hacker News Reader

I've been in the room when it happened. In one memorable incident, a junior trader I sat opposite bought 100 bn Japanese Yen instead of 10 bn. His excuse? "I lost track of the zeros". We'd only hired the guy because he had a PhD and "PhD's are smart" - lol. In his defense the UI was awful. He left soon after...

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Me too. Fatfingers happen much more often than the ones that are reported, partly because it's really hard to make UX that is functional for high-performing individuals trying to respond quickly in pressure situations while also protecting them from the consequences of errors.

For example, in one old FX trading system I know about you would type in the cross you wanted (eg say GBP if you wanted GBP/USD) and the amount and then if you hit enter it would execute. If you hit F5 it would execute that number of million of that cross. So say you wanted 10 million, you could type 10000000 and hit enter or you could just go 10 F5 and it would immediately execute 10 million. (ie if you hit F5 you didn't also need to press enter).

F6 was the same, but for billion. And yes it originally had an "are you sure?" chicken box but there was only one flag to disable all chicken boxes and one of the chicken boxes on another part of the system was such a constant pain in the ass that everyone had chicken boxes disabled. So if you fatfingered and hit F6 when you meant F5 you could literally execute a thousand times as much as you intended.

Other than massive wrong amounts, the other one I've seen a lot is people buying something when they thought they were selling and vice versa.

What is a "chicken box"?

A dialog box allowing the user to “chicken out” if they have second thoughts about some important action. Usually they say something like “Are you sure? yes/no”

Thank you!

Japanese uses different "groups" of powers of ten, maybe that tripped him up?

1; 10; 100; 1 x 1000; 10 x 1000

versus

1; 10; 100; 1000; 10000; 1 x 10000; 10 x 10000; 100 x 10000

https://en.wikipedia.org/wiki/Japanese_numerals#Large_number...

No, the gui input field das just 100000000000 vs 10000000000. Oops

So 2048 instead of 1024?

Good one!

without any dots? in that case "losing track of zeroes" seems a valid excuse

PhD's are usually smart. Your business was not, for allowing 100 billion Yen trades by manually entering 12 digit numbers with no punctuation.

Most of exchanges and brokers have a dialog window “Looks like unusual order with high price impact - do you really want to execute yes/no”

So definitely an UI issue.

A "fat finger" of only 10x is not that much of a fat finger and may not be detected for it's probably nothing out of the ordinary compared to the brokerage account's size. The fat finger in TFA, however, is a quite bigger fat finger: $444 bn instead of $58m.

That's 10 000x. That one is, indeed, a UI issue.

Also on fat fingers everyone will find this hilarious

https://thedailywtf.com/articles/Special-Delivery

That's not just an UI issue, the backend system responsible of executing the order should have caught the out of limits order.

Except that apparently they had such warnings for individual trades, but the bundle was implemented as "for(trade in bundle) transact(trade)". Which design has a certain appeal, standing on the shoulders of the peculiar handling of each trade, but with the terrible flaw that the bundle is never considered in its totality.

How do you buy 10,000,000,000 (let alone 10x that much) of something as a junior trader without someone signing off on it? There's nothing at all to stop catastrophic actions being taken by anyone in the organization?

At the time, no. There wasn't any checking. And while it looks like a lot, it wasn't insanely expensive to unwind. Sometimes these kind of mistakes make money. My own 'mistake profit /loss' was around +1m USD.

Yen was probably around hundredth of euro or dollar. So it is 100 million or billion worth of very liquid currency. Very likely among the most liquid trade pairs. As such you need to trade big to make money there. Get timing right and you make it, get it wrong and you lose some.

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