
Finance sites erroneously show Amazon, Apple, other stocks crashing - doener
http://www.marketwatch.com/story/finance-sites-erroneously-show-amazon-apple-other-stocks-crashing-2017-07-03
======
nopzor
This story isn't emphasizing an important point: the stock price of many tech
companies - amazon, google, Microsoft - were pegged to exactly $123.46 for
multiple hours.

This is likely 123.456 rounded to 2 decimals.

To me this smells like a software testing bug or hack, rather than "stocks
crashing"

~~~
dhbanes
I saw it pegged at 123.47

~~~
beejiu
Stocks have two prices. I guess this would be reflected in test data.

~~~
hkmurakami
Bid/ask?

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bbgm
As some have suggested, Nasdaq is confirming that this was test data that got
propagated to third party aggregators.

[https://mobile.twitter.com/Nasdaq/status/882054148413325313](https://mobile.twitter.com/Nasdaq/status/882054148413325313)

[http://www.nasdaqtrader.com/TraderNews.aspx?id=utp2017-05](http://www.nasdaqtrader.com/TraderNews.aspx?id=utp2017-05)

~~~
cm2187
Using production systems to run tests... What could go wrong?

~~~
humanrebar
It's actually considered best practice in various categories of technology to
run tests on the production systems.

[https://en.wikipedia.org/wiki/Built-in_self-
test](https://en.wikipedia.org/wiki/Built-in_self-test)

~~~
noir_lord
When done intentionally.

I've seen lots of tests 'escape' their environment for a bunch of reasons
(tests got sent to production with a deploy, human was on the wrong machine
and ran a manual test command etc etc).

It's almost impossible not to screw up at some point, I try to focus on
minimising the small mistakes (airline pilots have commented that it's not the
first problem that kills you it's the second one).

~~~
ethbro
That's why artificially differentiated steps are critical. If the "deploy to
test" procedure looks exactly like the "deploy to prod" procedure, except with
different servers, then you're asking for human error.

Ensure the test deploy procedure will _always_ fail if run against prod
targets when half-asleep. Whether it's something like requiring a different
config setting or a reload or an account switch. Anything that breaks the
process-as-usual.

------
trothamel
One nice thing about SEC-regulated markets - unlike the various cryptocurrency
markets - is that it's possible for trades to be rolled back if they are
"clearly erroneous". That isn't perfect - if the data is only a little off, it
might not be possible to get a trade rolled back - but it tends to limit how
much havoc is called.

[https://www.sec.gov/news/press/2009/2009-215.htm](https://www.sec.gov/news/press/2009/2009-215.htm)

(My understanding is that trades can also be rolled back in the case of
security breaches, at least at the exchange and broker levels.)

~~~
bendbro
Why can't majority participants in a crypto currency agree to roll back?

~~~
valarauca1
The majority of participants do not in a crypto-currency.

Only the majority of the hashing power.

~~~
jstanley
If a majority of participants rejected blocks that were on a chain that did
not rollback the erroneous transaction, then the hash power would be forced to
follow.

I believe the term for who decides is the "economic majority".

------
hbcondo714
> The problem may have originated with data services providing Google and
> Yahoo their financial information

I'm sure Google and Yahoo pay a small fortune for this data so I'm wondering
if they are aware of the situation and holding these data services companies
accountable or not.I'm also sure these data companies sell their data beyond
information sites to investment firms & others that make buy/sell decisions
based on this data. Yahoo does disclose[1] that they get some data 'direct
from exchange' though.

[1] [https://help.yahoo.com/kb/finance-for-
desktop/SLN2310.html?i...](https://help.yahoo.com/kb/finance-for-
desktop/SLN2310.html?impressions=true)

~~~
OskarS
I'm fairly certain they're aware of the problem :)

And yes, I bet this is going to lead to some interesting meetings between them
and the data providers.

------
cbanek
I've actually seen a number of times where Google Finance has a daily low that
was never reached or a high that wasn't shown on the graph (sometimes many
percentage points away). It's also notoriously bad when there's a gap up or
down, and will sometimes cut out various parts of the graph.

But still, seems to be one of the better ones out there, as I still use it.
Just don't treat it as authority.

Another interesting example of questionable data is the premarket CNN feed at
([http://money.cnn.com/data/premarket/](http://money.cnn.com/data/premarket/)).
I have sometimes seen a stock trading premarket down 99%, which almost always
looks like an off by some factor of ten of the price.

~~~
pishpash
Google Finance does not even have a working price plotter, that's pretty awful
in a basic way.

~~~
vpribish
and their financial news is flooded to uselessness with bot-written "stories"
from sites like "The <placename> [register|tribune|bulletin|news|alert]". The
service is pretty garbage now.

------
vpribish
This was a market half-day: exercising some code-paths that haven't been used
since the day after thanksgiving '16\. I do find it surprising that google and
yahoo are both affected, as they used to have very different patterns of stock
data errors (yahoo was much higher quality).

------
grondilu
Sometimes I wonder if it would make sense to place long-term buy orders at a
ridiculously low bids. Just in case.

~~~
comboy
On Bitcoin exchanges, sure. But here I think there's too much liquidity and
automated trading.

~~~
MichaelDickens
I believe the recent Ethereum flash crash demonstrated that this strategy
wouldn't work for cryptocurrency either. Ethereum price dropped to $0.10, but
it rebounded in about 5 seconds because trading algorithms put in lots of bids
at the really cheap price.

~~~
j_s
It did work, but not for many.

[https://news.ycombinator.com/item?id=14611653](https://news.ycombinator.com/item?id=14611653)

[https://news.ycombinator.com/item?id=14690908](https://news.ycombinator.com/item?id=14690908)

------
rnprince
This could be the beginning of a thriller movie. A nefarious hacker group
demonstrates a powerful zero-day for a dangerous client by creating national
panic over stock prices.

------
thomnific
This is silly. Blame the third-party providers on this one, for using exchange
prices during a holiday when the exchanges are closed ...

------
doener
"Will Briganti, a spokesman for Nasdaq, was unable to immediately comment on
the situation."
[https://www.bloomberg.com/amp/news/articles/2017-07-04/nasda...](https://www.bloomberg.com/amp/news/articles/2017-07-04/nasdaq-
stocks-show-exaggerated-movements-in-after-hours-trading)

------
traviscj
One of my grad school classmates spent some time in finance and always used to
say something like "your best results are really just bad input data". This
has proved a worthy maxim many times over.

------
honestoHeminway
What if a multi-government coalation broke out of the lobbyism hypnotization
and would split up amazon. Could such a drop be realistic?

------
gchokov
Black Monday - fake news edition.

------
ams6110
And we trust that software can drive our cars for us?

~~~
Flammy
Stock tracking websites don't need to be perfect, just need to be better than
the humans they replaced. Faster, free, and less errors doesn't mean they must
be error free.

Self driving cars just need to be better than humans, and given the number of
teens and senior citizens on the road...

~~~
ams6110
As someone contemplating the purchase of one, a self-driving car needs to be
better than _me_. That's a higher bar than better than _average_ even if it's
not objectively correct.

~~~
stale2002
Do you ever use a taxi?

Because if you do, you are putting your life into the hands of someone who
could be a much worse driver than you.

Instead of putting your life in the hands of a terrible taxi driver, would you
put it in the hands of software that is on average better than a taxi driver?
You are in a taxi, so you don't get to choose to drive it yourself.

~~~
goodplay
Not gp, but I would personally expect a taxi driver to be better than me
seeing the amount of time the diver spends on the road. The driver wouldn't be
profitable otherwise.

That said, I also mirror gp in that any self-driving car must be at least
better than myself for me to trust it. I imagine that's a sentiment shared by
many people.

~~~
yellow_postit
I agree this is the natural bar, but don't know how to reconcile it with the
average person believing they are a better driver than average
([https://en.wikipedia.org/wiki/Illusory_superiority](https://en.wikipedia.org/wiki/Illusory_superiority))

------
kwelstr
Wow, that's crazy! What algorithm did this, or maybe it's some scheme
manipulation for profit? You can never be sure when something like this
happens, flash stock crashes have a history that's muddy at best. :/

~~~
Xorlev
It's just a data feed error. The markets have not actually moved.

