BlackRock's Bitcoin ETF has achieved a significant milestone, reaching $100 billion in assets under management (AUM) in just 400 days, a record pace compared to Vanguard's VOO, which took 2000 days to reach the same mark. This rapid growth underscores the increasing institutional adoption of Bitcoin, transforming it from a speculative asset to a mainstream investment vehicle. The approval of Bitcoin Spot ETFs in January 2024 has accelerated this trend, with BlackRock's IBIT leading the charge. The ETF's swift ascent highlights a shift in market infrastructure and investment strategies, as noted by Bloomberg's senior ETF analyst Eric Balchunas. Despite recent volatility, with Bitcoin ETFs' AUM dropping over $40 billion amid price fluctuations, the overall trajectory suggests a growing legitimacy and acceptance of digital assets in traditional finance. Vanguard's recent decision to allow Bitcoin spot ETF investments further indicates strong demand from institutional investors. As regulatory clarity improves, the momentum for Bitcoin ETFs is expected to continue, potentially outpacing traditional assets like gold ETFs.