Well, you can only change your trade via the phone prior to the 3:55 cutoff, and mb's question was about the signal changing after the market closes.
If you are trading directly with Rydex, then yes, you have the option of placing a trade before the 10:30 est cutoff the next day for the 10:45 pricing, to get aligned with the Merlin signal, if you find yourself positioned against the signal because it changed from the prelim after the close. I have done that successfully myself. Since Merlin's stats say that trading the 10:45 next day pricing is profitable, I think its probably a winning strategy to do so.
And, as of this week, some brokerages will now allow you to trade the morning Rydex pricing. I believe Fidelity is one of them. So now, you don't have to have an account directly with Rydex to do this.
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