Grayscale's Ethereum Trust issues common units of fractional shares which represent ownership in the Trust. The trust issues shares to accredited and authorized investors from time to time, with no set ongoing redemption program, in exchange for Ether.
This chart plots the average weekly premium in the total value of Ethereum Trust shares (ETHE) to the Net Asset Value (NAV) of the Trust holdings of Ether, pre-Spot ETF launch.