It took me a couple versions to try and fix this an eventually settled on version 3 which I have been using on my own for the last few months. You can see in the comparison chart above it does a much better job of capturing backwardation moves and extreme contango. Below is a comparison of how it performed vs. Version 1 during December XBTZ19
In addition I have added high/low lines that can be used to understand the amount that premium/discount has moved in a specific time frame. For example, the big drop Bitcoin had on September 24th, XBTZ19 went from +$273 contango to -$247 backwardation = $520 move! This move was in addition to the spot price move which was almost -$1,700 from high to low and -$1,100 from open to close. See below:
The high/low lines can also be removed from the chart by unchecking a box in the input tab.
The last update is the ability to lock the spot price to be XBT (index) no matter what chart you pull up. This can be useful if evaluation XBT correlation to other bitcoin derivatives such as GBTC or . You can also disable this feature in the input tab, which will then just calculate based on the current chart you are viewing.
Current Contracts (December 2019)
Blue = XBTM20
Orange = XBTH20
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