[intronic]

Could you please explain this complexity? ELI5 even?

You never settle the trades? Dividends etc?

Hmm maybe I am 5...

Edit: ok yep so I guess what if they repeated the analysis leaving some time around open/close for chance of trades to settle, would the effect disappear or would this chance beef the key factor for the reported gain?

[kgwgk]

Settlement is when you actually own the stock you bought and the seller actually gets your money. That happens a couple of days after the trade. In the meantime it’s just “as if” but not quite and that has practical consequences. For example you can’t take your money out of the brokerage account until it’s really there.

[intronic]

Thanks! I was figuring this out just now as well thanks.

The analysis is flawed if it doesn't include this as the gains they describe seem essentially unrealisable.

So is the real issue that maybe someone has immediate settlement when the rest don't?

[kgwgk]

That would be an issue only a few days per year - and not at all for stocks not paying dividends.