Bitcoin ETFs recorded a one-day net inflow of 1,917 BTC, worth $147.42 million, in the Sept. 15 update. Over seven days, Bitcoin ETFs remained negative with net outflows of 4,372 BTC, valued at $336.16 million. Ethereum ETFs posted stronger weekly momentum, adding 38,547 ETH, or $95.44 million, over one day. Seven-day net inflows reached 89,621 ETH, worth $221.91 million.