Since BitMEX launched on 24 November 2014, cryptocurrency derivatives trading exploded. I tried in vain to seduce various venture capital firms with the vision of the future that was all about derivatives trading. At that time, succour was not forthcoming; however, I could not be more pleased with my failures now standing in 2019.
 
The BitMEX XBTUSD perpetual swap and various other contracts traded on OKEx and Deribit are of the same ilk. These contracts all allow you to trade a fixed USD amount of Bitcoin. We call these inverse derivatives contracts. Many OG traders have heard me speak at length about the subtle yet profound implications of this contract structure. However, as many new traders now try their hand at derivatives trading, a refresher course is necessitated.
 
Contrary to popular belief, I don’t delight when I see the BitMEX Rekt twitter feed going bananas. I’m long-term greedy. I would rather you enjoy a long trading career earning a profit and paying BitMEX trading fees along the way, than blow up your equity capital during a liquidation. Therefore, it is in mine and BitMEX’s best interest that our traders are sufficiently educated about best trading practices.
 
I love our traders, but when I hear people smile and laugh about getting liquidated it makes me cringe. A real trader practices proper risk management, and that means never being liquidated.
 
You Gotta Go Down, To Go Up
 
Convexity or gamma is the second derivative of a contract’s value with respect to price. Used correctly convexity can supercharge your portfolio’s returns. However, if you do not understand how convexity affects a derivative you trade, you will get rekt repeatedly.
 
With inverse contracts, the margin currency is the same as the home currency. I will use the XBTUSD contract throughout this post.
 
Home Currency: XBT (Bitcoin)
Foreign Currency: USD
Margin Currency: XBT
USD Value: 1 USD
XBT Value: 1 USD / Price (XBT/USD exchange rate or .BXBT index)
 
I will dwell on how the XBT exposure of a long 100,000 contract position changes with respect to the price (.BXBT Index).

First, let’s look at the long side. In bull and bear markets, these will most likely be speculators. This makes sense because being long Bitcoin offers asymmetric returns. Bitcoin can rise to infinity, but can only fall zero. It is better from a return on equity perspective to go long the bottom, then go short the top. Those who picked up ETH below $100 know this acutely. Therefore, coupled with leverage, on the margin, longs in most market environments will be predominately speculators.

The first chart shows XBT PNL profile and curvature. The straight line is the PNL %  return if the contract moved in a linear fashion, the curved line is the long inverse contract position’s PNL % return. What you immediately notice is that you will lose more money when the market falls, and make less money as the market rises. This is suboptimal as you must post margin in XBT. Thus, your margin requirements increase in a non-linear fashion, and this is why longs get rekt quickly in a falling market. 

Now let’s examine the short side.  In bull and bear markets, these will most likely be hedgers and market makers. In both cases, these market participants want to lock in the USD value of Bitcoin. With inverse contracts, a long physical Bitcoin position coupled with an equivalent short XBTUSD position creates a synthetic USD position. If 100% of the physical Bitcoin is placed at cross-margin with BitMEX, you cannot be liquidated.

Unlike the long side, shorts benefit from positive XBT convexity. Shorts make more and more XBT as the price falls, and lose less and less as the price rises.

The take away from these two examples is that long speculators will be liquidated faster on the way down. This explains why dumps in these derivatives dominated markets are now more extreme than pumps and will continue so long as inverse style derivatives dominate the cryptocurrency derivatives markets.

The CME contract has a fixed XBT exposure regardless of the price, and the USD exposure varies linearly with respect to price. While this is great for USD benchmarked investors, it becomes problematic for those hedging their exposure. Bitcoin purchased to hedge a short CME position cannot be used as collateral with the CME. This presents some challenges for hedgers who hold physical Bitcoin, and market makers who must divide precious capital between derivatives and spot markets with no cross-collateral relief.