Thank you for your detailed analysis. This change will indeed not change the liquidation risk as we don't change the liquidation price calculation.
However it will not lower the swap demand by 40 to 100%. It would currently lower it by a very small % (because most of our long users don't hold any USD as collateral). But even this small decrease in demand is nothing compared to the increase of demand resulting from the other change: the need to backup unrealized swap or pay it every day. The amount of unrealized swap is really high enough to outweight the amount of USD in trading wallet by a fair amount. However this will be smoothed out over the first days after the change to avoid spike as much as possible.
So long story short: our changes will initially lower a bit the swap demand, then in 2 to 3 days increase it by more.
Then of course there is the normal fluctuation of margin longs and the options that traders will chose for their unrealized swap which makes predictions only approximate.
Thank you for the auto-lend bot, it is a very good idea. I think initially it will just be based on the current asks with maximum and/or minimum rate to lend to.
Best regards
Raphael
Bitfinex team
Raphael, thanks for a great response. I am a little shocked to learn that most long users don't hold any USD collateral (though it makes sense if one's objective is to be as long BTC as humanly possible); for me this is the missing piece of the puzzle. Considering only USD as collateral for leverage calculations means that the bounds for collateral to position cost, rather than being 1 and 2.5, are actually 1 and infinity (the latter being the case where the whole margin balance is funded with Bitcoin). So the bounds on the drop in demand are 0% and 100% (not very informative bounds!). And you say that most leveraged long positions are based on BTC alone, so we can expect the drop to be closer to 0% than 100%. Good to know.
The fact that there is so much unrealized swap interest payments and that some of that is going to have to be paid for by selling BTC (since outstanding swap interest > USD collateral balances) makes me a little nervous. Have you thought much about your methodology for smoothing this out? What is your plan?
Say for example someone who has only BTC collateral, which you stated is very common. Say they have 5BTC collateral, a 10BTC open position, and $500 in unrealized swap interest (this would correspond to opening their position about a month ago say). If they have to pay the swap interest all at once, then 0.83 of their bitcoin, over 8% of their position, will have to be liquidated. How do you plan to amortize this?
Glad you like the auto-lend bot idea. I wrote up a pseudo-code design to do this but haven't yet got around to writing an actual bot implementation. Would love to see it as a standard feature though. Having both buy and sell side automation would greatly increase the market efficiency, to the extent that you could possibly even remove the FRR feature (since at the time of placing an offer you are getting the market rate). Then again perhaps an auto-lend bot would lead to a natural decline in the use of FRR, ie the market will decide.