Hi,

I wrote code that prints call and put options delta of SPY and I compare it to the values in optionet explorer (which I know are correct).
the call options delta are accurate, but the PUTs are not.
For example:
2020-01-02 09:31:00 SPY   200221P00316000, strike: 316.0, Delta: -0.21
while in optionet explorer the same option, at the same time, has 30.11 delta.
why there is such difference?
Thanks,

from QuantConnect.Securities.Option import OptionPriceModels from datetime import timedelta class LongStrangleAlgorithm(QCAlgorithm): def Initialize(self): self.SetStartDate(2020, 1, 1) self.SetEndDate(2020, 2, 1) self.SetCash(100000) equity = self.AddEquity("SPY", Resolution.Minute) equity.SetDataNormalizationMode(DataNormalizationMode.Raw) # required when working with options option = self.AddOption("SPY", Resolution.Minute) self.symbol = option.Symbol # set our strike/expiry filter for this option chain option.SetFilter(-40, 40, timedelta(45), timedelta(55)) option.PriceModel = OptionPriceModels.CrankNicolsonFD() # both European & American, automatically # this is needed for Greeks calcs self.SetWarmUp(TimeSpan.FromDays(50)) #TODO: better understand how much time is required def OnData(self,slice): if self.IsWarmingUp: return if not self.Portfolio.Invested: self.OpenStrangle(slice) def OpenStrangle(self, slice): call_option = self.FindOptionByDelta(slice, OptionRight.Call, 0.2) put_option = self.FindOptionByDelta(slice, OptionRight.Put, 0.2) if call_option != None and put_option != None: #self.PrintOptionContract(call_option) #self.PrintOptionContract(put_option) self.Sell(call_option.Symbol ,1) self.Sell(put_option.Symbol ,1) # find the option with the closest delta the input parameter def FindOptionByDelta(self, slice, optionType, delta): for i in slice.OptionChains: if i.Key != self.symbol: continue optionchain = i.Value options_by_type = [x for x in optionchain if x.Right == optionType] self.PrintOptionContracts(options_by_type) contracts = sorted(options_by_type, key = lambda x: abs(x.Greeks.Delta - delta)) if len(contracts) == 0: return None #no option was found return contracts[0] def PrintOptionContract(self, contract): self.Log(contract.Symbol.Value + ", strike: " + str(contract.Strike) + ", Delta: " + str(contract.Greeks.Delta) + ", Vega: " + str(contract.Greeks.Vega) +", AskPrice: " + str(contract.AskPrice) + ", Underlying Price: " + str(contract.UnderlyingLastPrice)) def PrintOptionContracts(self, contracts): for contract in contracts: self.PrintOptionContract(contract)