enter image description hereCan someone explain what this large negative spike in this stock chart is in after-hours trading?

It almost looks like a data glitch to me, since the value before and after the spike are almost exactly the same, but I'm wondering if it's something more significant.

I occasionally see strange anomalies like this when I check a stock and it seems strange.

Other sources:
enter image description here
Also in this table here from NASDAQ. That page is updated dynamically, so here is a screenshot of the current data:

enter image description here

If it's a data glitch, it must be in the primary data source that everyone else relies on.

  • $\begingroup$ As you said, most likely an error of some sort. First thing to do would be to check other data sources. $\endgroup$
    – Alex C
    Commented Jul 23, 2016 at 14:56
  • $\begingroup$ @AlexC: updated post to include more data sources. The "glitch" seems persistent. $\endgroup$
    – rothloup
    Commented Jul 23, 2016 at 20:35
  • $\begingroup$ Could this represent a major purchase by someone with stock options? $\endgroup$
    – rothloup
    Commented Jul 23, 2016 at 20:48

2 Answers 2


here's a print out from Bloomberg. The trade is only 250 shares and is flagged "AP" Also, the exchange is "D", which is the ADF. That means "Average Price Trade" reported on the ADF.

In English this means that this trade was tied to something else. Maybe someone had a small mistake that they had to correct for when pricing a larger chuck on TSLA options vs stock. This would just be a bit to clean it up. Also, notice the price. The fractional price is one that cannot be posted to an exchange.

enter image description here

  • $\begingroup$ NP. Usually those weird prints are tied to something else. $\endgroup$
    – JoshK
    Commented Jul 24, 2016 at 22:34

I tried yahoo finance as well. The "glitch" appears there too.

However all these sources get their data from the same place, the consolidated ticker.

My guess is that this is just bad data, given the fact that it's out of hours, and like you say the price almost immediately corrects to exactly the level before. It might be that the mid price being reported is (say) the average of the bid and ask, and at this time the bid side disappears for a short while.

Btw, when there is a proper "fat finger" error the price will move a bit more gradually back to fair-ish value often with a few trades at levels on the way down/up.


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