Bitcoin has twice defended the roughly $81,500 cost basis of U.S. spot ETF investors, even after $681 million in net ETF outflows last week and another $65 million shed on Monday. Glassnode Flags $77.5K if Bitcoin Loses ETF Cost Basis Bitcoin is testing whether institutional ownership has permanently changed the character of its market. The cryptocurrency has bounced twice from roughly $81,500, a level Glassnode identifies as the aggregate cost basis for U.S. spot bitcoin ETF investors. That matters because BTC spent much of this year below the threshold, while its May rally stalled just underneath it. What was once resistance is now acting as support. More strikingly, bitcoin has defended the level despite $681 million in net U.S. spot ETF outflows last week and another $65 million outflow on Monday . If support eventually breaks, then Glassnode points to the true market mean near $77,500 as the next major level. ETF Cost Basis Becomes Bitcoin’s New Line in the Sand The resilience around $81,500 is notable because ETF flows have recently been working against bitcoin rather than supporting it. Vugar Usi Zade, CEO of MEXC, argued that institutional capital has nevertheless created a stronger structural floor. “Bitcoin is moving into a phase of institutional maturity, where the $80,000 mark has become the average cost for positions held by spot ETFs and custodial services,” he said. If major funds accumulated heavily around this zone, then declines toward $80,000 may increasingly attract buyers rather than trigger panic. Institutional positioning is not the only constructive signal. Bitcoin Magazine analysis comparing BTC with Federal Reserve net liquidity noted that bitcoin has recently outperformed the broader liquidity backdrop, even while maintaining a meaningful longer-term relationship with it. That is important because bitcoin has historically been highly sensitive to liquidity conditions. Recent performance suggests investor demand may be contributing more to bitcoin’s price action, rather than simply rising and falling with shifts in macro liquidity. Still, BTC remains exposed to broader financial conditions. Liquidity matters, even if it is no longer the only force driving the market. Two successful defenses of the ETF cost basis are encouraging. Defending it while ETFs are recording net redemptions is an even stronger test. However, the $81,500 mark is not guaranteed to hold. Continued ETF withdrawals could eventually overwhelm underlying spot demand. For traders, the setup is increasingly clear. Bitcoin’s price holding above $81,500 despite persistent outflows would reinforce the argument that institutional positioning has created a new BTC floor. Losing it would quickly shift attention toward $77,500. The key question is no longer whether ETFs can push bitcoin higher. It is whether bitcoin can hold the ETF cost basis while money is leaving the funds. Blackrock Drives $150M Bitcoin, Ether ETF Selling U.S. crypto ETFs opened the week under renewed pressure, with bitcoin funds losing $65.40 million and ether ETFs extending their…