PANews reported on September 20 that according to CryptoSlate, BlackRock has modified its custody agreement with Coinbase, requiring withdrawals to be processed within 12 hours. According to the SEC filing submitted on September 16, the modification mainly involves BlackRock's iShares Bitcoin Trust ETF, which aims to improve the withdrawal process and asset management during unsettled transactions. The agreement stipulates that in the case of outstanding transaction credits, Coinbase Custody must process the transfer of Bitcoin from the custody account to the blockchain address within 12 hours of receiving the instruction.

The move is reportedly intended to respond to recent rumors that Coinbase is using letters of debt rather than Bitcoin to support its ETF, but Bloomberg analyst Eric Balchunas denied the allegations.