GBTC holdings USD market value

This script estimates GBTC bitcoins per share, rather than hardcoding as in other scripts. Its result is an estimate of GBTC holdings USD market value.

Per share bitcoin estimates are adjusted by 2.0% / 365 per day from 2019 year end holdings. Calendar year 2019 ending bitcoins and shares were 261,192 bitcoins and 269,445,300 shares. From the 2019 Form 10-K: 'The Trust’s only ordinary recurring expense is the Sponsor’s Fee. The Sponsor’s Fee accrues daily in U.S. dollars at an annual rate of 2.0% of the Bitcoin Holdings.. The Sponsor’s Fee is payable in Bitcoins to the Sponsor monthly in arrears.'

No attempt is made to account for leap years.

Per share bitcoin estimate is converted to USD market value by multiplying by the simple average BTCUSD price at Coinbase and Bitstamp. Grayscale uses the TradeBlock XBX index, a volume weighted average of Coinbase Pro, Kraken, LMAX Digital and Bitstamp prices.

Spot checks vs archive.org captures of daily bitcoins per share and the chart on Grayscale's site:

• The estimate for market close January 22 2021 is 0.00094899 bitcoins per share, the published datum on Grayscale's web site was 0.00094898. The estimate matches at 20:30 rather than at 16:00.
  The estimate for December 31 2018 is 0.000988965 vs a published 0.00098895.
  The estimate for December 29 2017 market value is $14.58 vs $14.65.
  The estimate for December 30 2016 market value is $0.99 vs $0.98.
  The estimate for January 4 2016 market value is $0.46 vs $0.45.
  

No estimates before 2016.

The default style is to draw a blue line with two thirds transparency outside market hours and for first/last minutes of trading, switching to daily or greater periodicity hides this.

No warranty is expressed or implied, I am not a lawyer, etc etc etc.

This is not investing advice. Always do your own due diligence.