i would like to take a 35 btc loan, and return 40 btc if/when bitcoinica pays back my 40 btc.
i will return nothing before bitcoinica pays me back.
Maybe Zhou Tong or the Bitcoin Consultancy will loan you the 35 BTC, because that's an awfully bad deal for anyone else lol
Good luck
should i provide 50% back guarantee by christmas?
None of that will solve the "i will return nothing before bitcoinica pays me back." problem, because the most certain is that you won't get a dime back.
Even if you guarantee 50% back by Christmas, they will still lose.
i would take the offer of loan 30btc payback 40btc, and 50% (15btc) by christmas, if i had btc enough, and the loan taker was a reputable forum member.
Personally I think Bitcoinica has a 10% chance of paying back, so I'd buy your debt for less than 4 BTC. Not 35.
60% of the time, the loaner would get 15 BTC back on their 30 BTC loan. That's -15 BTC. * 60% = -9.
40% of the time, the loaner would get 40 BTC back on their 30 BTC loan. That's 10 BTC. * 40% = 4.
Add them up, and on average, over an infinite number of universes, 40% of which Bitcoinica paid back their customers in full, the loaner would lose 5 BTC.
This is with the IMO very optimistic 40% odds.
For anyone considering this, if I thought Bitcoinica had X% chance of paying back, and the price of the debt was Y, I would not buy 40 BTC of debt with 15 BTC guaranteed payback if
X*(40 - Y) + (1 - X) * (-Y + 15) <= 0
So my 10% odds comes out to 17.5 as the maximum I'd be willing to pay.