[RinaseaofDs]

I can see one useful reason for this regulation.

Early hackers used to target banks. They would set up accounts, then set up transfers of small amounts of money (usually a penny or something smaller) into this account. They would then clean and close the account.

Limiting electronic transfers would put a stop to something like this.

Don't throw bottles or cans, I'm just envisioning one possible reason why the regulation may be there. Why 6? Who knows.

[The Raven]

I think this is because of "time traders" mostly with 401k's - they found a way to cash in on some time delays. I think there were 6 or so employess at one of the big companies making a killing and then the other 9,999 employees realized it was THEIR money getting ripped off.