US Spot Bitcoin ETFs See Best Week Since April as Flows Hit $1B

Demand for US spot Bitcoin exchange-traded funds (ETFs) accelerated sharply over the past week, according to Bloomberg ETF analyst Eric Balchunas. The renewed inflow momentum arrives after months of uneven participation, rekindling a key question for market watchers: whether institutional appetite is broadening again—or whether this is a temporary swing in investor behavior.

At the same time, the discussion around custody remains unsettled after a high-profile Coldcard hardware wallet incident in which attackers reportedly stole about $116 million in Bitcoin. The security breach has renewed attention on the trade-offs between self-custody and regulated products like spot ETFs.

Key takeaways

• Bloomberg’s Eric Balchunas said spot Bitcoin ETFs drew about $1 billion in net inflows for the week, the strongest since April.
• Balchunas described the rebound as the third-best weekly performance since last October—an era he called Bitcoin’s “silent IPO.”
• A Coldcard security exploit linked to vulnerable firmware has put self-custody concerns back in focus.
• Balchunas suggested the hack could help drive some investors toward spot ETFs, though he cautioned that the link is not proven.

Spot Bitcoin ETF inflows rebound after a patchy stretch

Balchunas posted that US spot Bitcoin ETFs took in roughly $1 billion in net inflows over the week ending Saturday. He said the result was the strongest weekly showing since April and ranked as the third-best week since last October, when he referred to Bitcoin’s “silent IPO.”

The “silent IPO” framing comes from investor Jordi Visser, who popularized the idea in November. In Visser’s view, early Bitcoin holders were gradually selling into expanding demand from ETFs and other institutional channels. The effect, under the theory, was enough additional supply to keep Bitcoin comparatively constrained even as new capital continued to enter via regulated vehicles.

That context matters for interpreting this week’s improvement. The source notes that ETF flows had deteriorated in earlier periods of stronger demand, making the recent rebound more noticeable. For traders and portfolio managers, consistent ETF inflows tend to be easier to track and model than broader, decentralized participation, so a return to stronger weekly demand can quickly change sentiment around the near-term positioning of institutions.

Coldcard hack refreshes the custody debate

The ETF story is unfolding alongside a major security incident involving Coldcard, a Bitcoin hardware wallet developed by Coinkite. The exploit reportedly resulted in about $116 million worth of Bitcoin being stolen, with the attack tied to a flaw in how affected devices generated wallet keys. According to the earlier coverage referenced in the source, attackers were able to compromise funds held in wallets created using vulnerable firmware.

On Friday, Balchunas argued that the Coldcard incident could ultimately strengthen the case for spot Bitcoin ETFs—particularly for investors who prefer not to manage the technical responsibilities that come with self-custody. He pointed to the observed surge in ETF inflows following the hack as a possible connection.

In his comments, Balchunas explicitly acknowledged the limitations of drawing conclusions from timing alone. “Correlation does not imply causation,” he said, but added that, over the long term, he can’t imagine there aren’t some investors who migrate from cold storage to ETFs.

For market participants, this is a meaningful mechanism to watch: a single security incident can influence risk perception across the broader custody ecosystem. Even when the affected devices are limited to specific conditions, the reputational impact can push some users toward a custody model backed by regulated intermediaries—especially those evaluating whether the operational burden of holding Bitcoin directly is worth the benefits.

What to watch next: whether inflows persist and custody concerns evolve

Even with this week’s strong ETF numbers, the key question is durability. Balchunas’ “silent IPO” concept suggests that ETF demand and investor selling behavior can interact in ways that keep price action subdued relative to capital inflows. The rebound in net flows therefore doesn’t automatically resolve the larger balance between new institutional purchases and supply from earlier holders—but it does reintroduce a tailwind to demand that was less pronounced in earlier weeks.

Separately, the Coldcard episode raises a second uncertainty: whether the custody shift Balchunas hinted at becomes visible in sustained ETF inflow patterns, or remains anecdotal. Investors watching the next cycle of weekly flows may want to compare whether inflows continue to strengthen over multiple reporting periods, and whether risk communication around hardware wallets changes in response to the incident.

Until regulators clarify broader standards and until the market sees how persistent the post-hack behavior proves to be, the combination of improving ETF demand and renewed custody concerns will likely remain a central driver of how Bitcoin’s institutional narrative develops.

Going forward, readers should track whether the next several weeks of spot Bitcoin ETF flows match this week’s strength—and whether custody-related headlines translate into measurable, sustained shifts in investor allocation between self-custody and regulated products.