Grayscale Investments plans to introduce a "mini" version of its Grayscale Bitcoin Trust (GBTC) with a fee of 0.15%, making it the cheapest among the 11 approved spot Bitcoin ETFs. However, Bloomberg analyst Eric Balchunas warns that these are hypothetical figures and could change before launch. The move comes as Grayscale seeks to stem the outflow of funds from GBTC since the launch of Bitcoin ETFs in January. The new Bitcoin trust shares are expected to be distributed to existing GBTC shareholders, with GBTC also contributing an undisclosed amount of Bitcoin to the new trust.