BitShares has many controls around market pegged assets (MPAs) and their ability to be “shorted into existence.” Some of those fields have long names and difficult to sort out abbreviations. I am hoping to prepare this document to help sort it out.
MCR – Maintenance Collateral (or Margin Call) Ratio
How it is used:
For the sake of simplicity, I will not include fees in this discussion.
Scenario 1: Extreme Risk Taker
MYTOKEN is currently valued at 20 BTS. MCR is currently set at 1.75. I have 100 BTS, and wish to create 1 MYTOKEN. I would need to put up at least 35 BTS to create 1 MYTOKEN ( 20BTS * 1.75MCR = 35 ), which I do.
So now I have 1 MYTOKEN, I also have 75 BTS, and 35 BTS tied up as collateral.
If the value of MYTOKEN rises in relation to BTS, my collateral ratio is now below the 1.75 minimum. Let’s say the value of MYTOKEN rises to 25BTS. My collateral ratio is now (collateral / ( debt * current price) =) 1.4, well below the maintenance level I need of 1.75. I will be forced to sell (a.k.a. margin called).
Scenario 2: A Conservative Trader
MYTOKEN is currently valued at 20BTS. MCR is currently set at 1.75. I have 100 BTS, and wish to create 1 MYTOKEN. I would need to put up at least 35 BTS to create 1 MYTOKEN (this is the same as Scenario 1). I put up 50 BTS as collateral to received 1 MYTOKEN.
With such a trade, I can calculate at what price MYTOKEN must rise (or BTS must fall) to in order to be margin called. That formula is (collateral / (debt * MCR). Therefore the price at which I would get margin called is (50 / (1 * 1.75)) = 28.5714BTS
MSSR – Maximum Short Squeeze Ratio
How it is used:
When margin calls happen, orders to purchase the asset I “shorted into existence” could dry up the current liquidity on the “sell” side of the market. If there are no sellers, the price of the asset could skyrocket, thereby leaving me to lose even more money.
MSSR helps with this. It is a safety mechanism for orderly markets. We will run the margin call of Scenario 2 above through the market. For this scenario, the MSSR is set at 1.1. That means that I will have to pay up to 10% above market price in order to lower my exposure. We calculated that the price at which I would get margin called was 28.5714BTS. With an MSSR of 1.1 that means that I will pay up to 31.4281BTS.
The order book currently has an order to sell 0.25 MYTOKEN at 29 BTS, and another order to sell 0.25 MYTOKEN at 32 BTS. That means the system will purchase the 0.25 MYTOKENs at 29BTS. My account will now have 0.75 MYTOKEN, and will have used 7.25BTS of my collateral for the purchase. That leaves my collateral balance at 42.75BTS.
After that purchase, the price of MYTOKEN would need to continue to rise to 32.5714 for my collateral ratio to again be low enough for yet another margin call.
How MCR and MSSR are adjusted
At the moment, the settlement price, MCR, and MSSR are provided by price feeds. The different feeds are used to derive an average that is used for all market participants at that time.