Significant (75%) End of Day jump in option price

External question — Personal Finance Stack Exchange Author: SolStack Original post: https://money.stackexchange.com/questions/120397 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I am fairly new to option trading so am having a hard time making sense of this... I had a $10 put option for VIVO with 02/21/20 expiration. As viewed in the Robinhood app, the option jumped from $1.90 to $3.10 ten minutes before market close on Feb 13. The underlying stock VIVO had been dropping from $8.20 to $8.06 over the course of the day but did not seem to be abnormally volatile. On Feb 14, the option opened at $1.90, right where it had been before the End of Day jump. 1) Did the option value actually increase to $3.10 before close on 2/13 or do you think this was a bug in Robinhood's software? 2) If the option did jump, what would explain the temporary increase of this magnitude? 3) Where can I find a historical chart or similar for this option (and others) to compare against what I see in the Robinhood app? Here are some screenshots from the app: VIVO $10 Put - Feb 13 1-Day Chart VIVO $10 Put - Feb 13 Position details VIVO $10 Put - Feb 13 Stats and Greeks VIVO $10 Put - Feb 14 1-Week Chart VIVO stock - Feb 13 1-Day Chart VIVO stock - Feb 13 Stats VIVO stock - Feb 14 1-Week Chart

External answer — Personal Finance Stack Exchange Author: Bob Baerker Original post: https://money.stackexchange.com/a/120398 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. 1) Did the option value actually increase to $3.10 before close on 2/13 or do you think this was a bug in Robinhood's software? No, this was not a bug. And no, your option's value did not actually increase to $3.10. The bid/ask widened from $1.80x$2.00 at 15:54:42 to $1.70x$4.50 at 15:55:06. The latter quote is what is found in your screen capture. Robinhood averages the bid and ask price and gave you a quote of $3.10 which is merely the midpoint of the bid and ask. When this happened, the bid of your put (what you could get for it if you sold it at the market's price) dropped from $1.80 to $1.70 and that 10 cents drop is a normal price fluctuation. 2) If the option did jump, what would explain the temporary increase of this magnitude? With illiquid stocks and options, the spread can widen as the close approaches (traders are pulling their orders). Another reason for the spread of a stock and its options widening so much would be a trading halt in the stock for pending news. There was no trading halt in VIVO yesterday. 3) Where can I find a historical chart or similar for this option (and others) to compare against what I see in the Robinhood app? A decent broker provides Time & Sales (quotes) as well as historical charts.