POLL - SS forcing you to keep new loan parts....

We're talking about two different scenarios.

The first, is referred to in SS's email "The main problem isn't gaming the pre-funding, but with people buying loan parts on the secondary market, and selling them within 48hrs - getting interest without ever putting money in SS."

The second is where lenders acquire large holding and don't balance their accounts within the grace period. SS stated quite a while back that they would, and subsequently confirmed that they had done so on occasion, cancel purchases and all interest accrued.

Edit: But as I said above, IMO, prevention of selling newly purchased loans alone will not remove the potential for profiteering.

Probably a few tax implications with that unless it was deducted from interest paid rather than charged.
Also because deposits aren't reconciled on the same day a deposit is sent it wouldn't work in practice.

I believe that a requirement for ISAs is that you need to be able to withdraw your money 'on demand'. There can be penalties for doing so and with non-liquid assets there has to be time to liquidate them. However, I do not think that an arbitrary hold period would be compatible with this.

We know that SS are keen to start providing ISAs. While it is possible that they might impose this on the non-ISA product, while not on the ISA, this would seem to be unnecessary complication.

If that (i.e. interest on 'forever floating' debit balances) is really the issue for SS then yes, the solution is clearly to not actually assign you the interest in the parts until they are paid for (by cash, or by selling other parts) .. for the 24 or 48 hours you just have them 'reserved', but they are not actually yours, as far as interest goes. The alternative suggested of charging 1%/month on debit balances (which amounts to the same thing) is tax/accounting wise rather trickier. This has to be saner and more direct than tying up sales for 7 days, which as  you say doesn't actually stop people selling something else, and still collecting extra interest.

If someone is really playing 'pass the parcel' every 48 hours, then just cancelling the offending account(s) would be fine by me too - I'm sure SS's T&Cs don't oblige them to deal with anyone they don't choose to.

If the problem is people 'reserving' parts on spec, to the disadvantage of others, then the solution is something different, but putting a 7-day lock on re-sales probably isn't it (again, just sell something else, and sit on the rump of what you didn't want until the 7 days is up).

I voted for 7 days but actually think it probably ought to be more. I can certainly see no justification for not putting in some sort of no-trade period or for that period being less than 7 days. If it reduces gaming and consequent SM distortion, that fully justifies it.  Yes, I game the system to try to get what I want, of course I do, but I'm prepared to live with the consequences of getting it wrong and would never bid more than I'm prepared to fork out if I have to.

Probably easiest to charge a daily interest (the same 12% pa) on any negative balance at midnight.  This should balance out any interest earned.

You can get your money back by closing but there are plenty that don't allow partial withdrawals. And plenty of them won't be that instant particularly if you want to preserve your allowances (they don't have to make them flexible)