That is because the Dec 20, 2019 $4.00 Put had some of the highest implied volatility of all equity options today.
Interesting article about Aurora's stock price and where it might be heading from here. $4.00 by December 20th seems like a long ways away right now, I don't see it going near there. If there's that much interest in the puts maybe I can sell some calls for around the same price.....
Read the full story here.....
https://finance.yahoo.com/news/options-traders-expect-huge-moves-135001575.html