At least one investor isn’t happy with the performance of the Grayscale Bitcoin Trust (GBTC), which holds more than 3% of all Bitcoin in circulation. So it's putting Grayscale on blast. In an open letter to the Grayscale board of directors published yesterday, investment firm Marlton took aim at GBTC’s discount to NAV (net asset value), calling it “abysmal” despite Grayscale’s attempts to bring the price up. Marlton, which says it’s a substantial GBTC holder, estimates the discount has lost GBTC stockholders $3.1 billion, even as investors are also paying a 2% management fee for the privilege. It’s asking Grayscale ... (full story)