Yesterday I had two positions where the bid/ask spread on one of the options was really bizarre. The one that is still easily visible is the eBay put oct19/oct26 35 strike calendar. The bid/ask for Oct19 is fine but on the Oct 26 it is really weird: P 34 1.87/1.94 IV 36% (OI 1040) P 35 0.91/2.98 IV 0% (OI 53) P 36 1.32/5.05 IV 15% (OI 2) P37 2.59/4.7 IV 0% (OI 57) This isnt just end of day variances - it persisted through the day and hence my put calendar shows a whopping loss as the Oct19 one is priced correctly. The same thing happened on my LLY position where I have a C OCT26 109 position that during the portion of the day that the stock was up practically a full dollar (which should have been a big plus for me) the bid ask spread on that option was huge 0.98/3.15 at some point whereas all other positions had bid/ask differences below 30 cents. The huge spread persisted until the stock retreated from its high after which the gap closed. By that time however my position moved out of profit again. I am not conceited enough to really fill victimised but the situation does seem illogical. If all bid/ask spreads widen that makes sense as some uncertainty may be at the bottom of it. Why would it occur on a specific option though?