SEC delays approval of multiple cryptocurrency ETF applications and seeks feedback, including the physical subscription mechanism for BlackRock Bitcoin ETF According to The Block, the US Securities and Exchange Commission (SEC) has announced the postponement of its decision on the physical subscription mechanism for the BlackRock Bitcoin ETF and has begun soliciting public opinions. If approved, this mechanism will allow investors to directly purchase and redeem ETF shares in Bitcoin instead of cash, improving trading efficiency. The rule revision submitted by Nasdaq in January this year showed that iShares Bitcoin Trust intends to adopt this model, but the SEC previously preferred a cash settlement mechanism. On the same day, the SEC postponed the approval of Grayscale Litecoin Trust and Grayscale Solana Trust and requested public opinion. The SEC also solicited public opinions on the 21Shares Dogecoin ETF on Tuesday.