The provided sources strongly support the assessment that the statement is true. The most authoritative and relevant sources—the official Federal Reserve website, its X (Twitter) account, and a Wall Street Journal transcript of a press conference—provide direct insight into the public statements of the current Chair, Jerome Powell. An analysis of these, combined with public knowledge of Powell's commentary, indicates he has consistently characterized Bitcoin as a speculative asset, not a store of value, and has highlighted its volatility. This stance is antithetical to "backing" it.None of the other sources, primary or secondary, offer any evidence to contradict the statement. The news articles from Reuters, The Guardian, and Bloomberg focus on market speculation related to potential Fed Chair nominees, not on statements from any past or current chair. The remaining sources are either market commentaries with no direct quotes or low-authority social media posts that offer no verifiable evidence. A public endorsement of Bitcoin by a sitting or former U.S. Federal Reserve Chair would be a momentous and widely reported financial news event. The complete absence of any such reporting across the provided sources makes it highly probable that no such endorsement has ever occurred. While the sources do not cover every public statement from every past chair, their collective silence on this specific topic provides strong circumstantial evidence supporting the original claim.