SPX weeklies: "https://www.cboe.com/tradable_products/sp_500/spx_weekly_options/specifications/" SPX Monthlies: "https://www.cboe.com/tradable_products/sp_500/spx_end_of_month_options/specifications"
.11 cents represents the risk of a big after hours move that would affect your decision to exercise the option. the time cutoff for that is about 530pm depending on the broker. if you want to model intraday you can do two things: determine the seconds until 530 and use that as time to maturity. You will probably over value the option because of all the non trading time or you can devote time to determining the value of the non trading time vs the trading time periods. personally I use days to maturity until the day of. but I don’t have to be super precise (like a bank or quant book would have to be)
Thanks. I had a mistake in the earlier quotes; They should be almost zero. But regardless of the cutoff time, I'm wondering why non-trading time matters for valuation? Shouldn't the options decay during non-trading hours as they do during trading hours? Do they decay differently during these two periods?
Technically they shouldn’t decay at all as there is not stock volatility. Decay is the price of expected gamma pnl. However they should decay something because you expect a lot of gamma pnl on the open. if the opening price was always equal to the previous close they should have no decay overnight otherwise that would be arbitrage
1) Lower commissions as you are trading 10X the size. (so percentage of trade to commissions is lower) 2) 60/40 Tax treatment for gains 3) No assignment risk (cash settled only) Plus, I have SPX option pricing data (CBOE LiveVol 60-sec quotes from 2004, and subscription) and have good IV derivation for indexes.
I see. I actually think it may make sense to consider trading and non-trading hours similarly as the opening gap can often be larger than the stock movement during the day.
Thanks. Is bid/ask spread an issue? I see larger bid/ask spreads in SPX options than SPY. For your IV derivation, do you evaluate trading and non-trading hours differently as newwurld suggested?
I ignore non-trading hours as the BID/ASK (which is used for pricing) is not valid at those times. The BID and the ASK is used to derive the expected value/price for the options, so when it widens, it is often not symmetrical, which adds error to the estimate for the option price. I do look at Spread/MID and when it increases too much, distrust the Price. For SPX this varies depending on the expiration, but any over 10% requires a strong stomach to trade. 2% to 5% seems to be OK. For the spread increase (Contrast SPX to SPY), it may be good to consider a 1 penny SPY spread is equivalent to a 10 cent SPX spread. I do not claim to be an expert, but just muddling thru and trying to make sense of it all.
I didn't mean to use quotes during non-trading hours, but whether to take non-trading hours into decay. For example, if an SPX option is trading and will expire tomorrow, do you consider DTE to be just the trading hours left or trading + non-trading hours left. I think that was what newwurld was referring to.