The charts on my system doesnt show the real change in the account on Octuber 11. I guess it’s because you took the last price of the option and not the bid price. Could you solve this problem plz?
http://geometric.collective2.com/
Funny, this issue hasn’t been mentioned before as far as I am aware and now twice in two days - I posted about exactly this problem yesterday!
http://collective2.com/forum?plus-is-in-minus-or-is-it
One of the main strengths of C2 is that it supports a very wide variety of trading instruments and markets which mirrors real life trading much better than any competition I’ve seen. The flip-side is that, in order to remain general, certain specifics have not been implemented; such as using published bid/ask for option pricing (which is what brokers do) instead of last trade (which is what C2 does).
I suspect we’ll have a long wait before C2 changes the way they report option prices, if it changes at all. So I’m afraid you’ll probably have to live with it, and so will I 
In fact, for a very long time, C2 did use the bid/ask spread when valuing options and marking them to market.
But we got a lot of complaints from people that the bid/ask spread for options (particularly illiquid ones) can be quite ridiculous at certain times.
So to reduce heartache, we value options using the last trade price. (To be clear, we still use bid/ask spreads within our Hypothetical Fill Engine; the last is used only for valuing open positions.)
So it seems we can’t make everyone happy all the time.
Probably the best thing to do is the following: to value options using the bid/ask spread unless the midpoint of the bid/ask is more than, say – I don’t know – maybe 20% away from the last?
I hope we don’t have to wait long, Dean!
It’s been explained why C2 uses actual prices received by autotraders to track performance of trades. But what is the rationale for using the last sale price to track performance of open positions? Matthew, can you answer this please?
If there are autotraders on a system, limit orders get converted by C2 to market orders anyway so the bid/ask are a much better approximation of the value of positions. It’s obviously more important with options but applies to thinly-traded stocks as well.
edit: I was posting this at the same time as Matthew so will reply to him below.
Ah, that does make sense, options spreads do get pretty wild at times. Your compromise idea sounds good.
Thanks for the response Matthew.
I don’t understand why anyone would complain about a high bid/ask spread - that is the reality for illiquid options out there in the real world! Of course, if you are day trading illiquid options the high bid/ask spread can completely kill any paper-trade edge the system may have. Maybe it was those people complaining?
It seems to me that the way it is now must be more wrong - I can instruct my broker to buy an illiquid option at the ask price at any time but the last traded price can be very different to that.
But they have use the bid price to draw the charts all the others days.
I dont know why this particular day it fail
