The assessment is primarily based on one highly relevant source. A Bitget news sitemap, which aggregates financial news, includes a headline explicitly referencing a CoinDesk report about 'BlackRock-linked wallets' moving a large sum of Bitcoin and Ether to Coinbase Prime. This piece of evidence, despite being from an aggregator, directly corroborates the core elements of the statement: the entities involved (BlackRock, Coinbase) and the assets transferred (BTC and ETH). While the exact amounts of 15,112 ETH and 249.5 BTC are not mentioned in the provided summary, the description of the event aligns perfectly with the claim.Supporting this, other sources, while not directly confirming the transaction, establish BlackRock's significant involvement in cryptocurrency. The Interactive Brokers list of shortable securities includes a BlackRock Ethereum Trust ETF, and a Coinbase price page mentions a partnership involving BlackRock for Bitcoin exposure. This contextual evidence makes a large transfer to a major exchange like Coinbase plausible.There is no conflicting evidence presented in any of the sources. The majority of the provided documents are irrelevant price pages or financial data that offer no information on the matter. The single, highly relevant source, combined with contextual support and the absence of contradiction, strongly suggests the statement is true.