None of that matters. If you buy before price is adjusted to reflect split, your account will be adjusted accordingly. Stock split and cash/stock dividend are not the same. Ex date means zero when it comes to split.
No the stock won't be 400 dollars tomorrow, the stock will be whatever it closes on the 28th. You need to figure out the how to do the math when we close on Friday next week.
You must own the stock by close of business on the 21. On close of business of the 28 you shares will be split into 5 shares and tradable on the 31st...
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