Here's a interesting comment on seekingalpha about the current GBTC discount:

https://seekingalpha.com/news/3669426-mulling-bitcoin-and-100k-is-grayscales-discount-a-buy-signal

"Three reasons Grayscale (GBTC) is trading at a whopping big discount to the bitcoin it owns: (1) New ETF products that don't charge a hefty 2% annual fee for holding your bitcoin may soon appear. (2) GBTC is not redeemable. If the GBTC discount becomes excessive, Grayscale still owns the bitcoin, but existing shareholders get nothing and can't get the bitcoin out. So far as I know, there is no mechanism to bring the share price into line with the bitcoin price, which is why Im not buying any more GBTC. (3) ARKK is likely being forced to liquidate its holdings due to redemptions. As ARKK holds its bitcoin in GBTC, forced sales into a declining market could be pushing down GBTC to a huge discount."

I had not considered the sale pressure from a possible ARK liquidation. I double checked ARK ETF's that have GBTC, and it is not ARKK. It is in ARKW (ARK NEXT GENERATION INTERNET ETF), where GBTC is the 3rd largest position (after Tesla and Square), at 8,309,914 shares with market value of  $344,030,439.60 for 4.77% weight of the fund.

GBTC has Shares Outstanding 692.3M, so ARKW holds 1.200% (8.309914M/692.3M). I'm not sure if ARKW selling a bit of their a little over 1% would cause such a large drop in GBTC premium.

But in any case, I think it might be a good time to add some GBTC!