U.S. spot Bitcoin ETFs just can't catch a break. After a solid seven-day inflow streak that brought in roughly $1 billion, the funds hit a wall on Thursday and Friday, shedding a combined $465 million. Friday alone saw $240 million in net outflows, following Thursday's $225 million exodus, according to Farside Investors.

The biggest culprit? BlackRock's iShares Bitcoin Trust (IBIT). It accounted for nearly $415 million of the two-day total, suggesting that institutions are using the market's most liquid Bitcoin ETF to quickly trim exposure.

Despite the late-week selloff, the funds still managed to eke out a weekly net inflow of about $34 million, thanks to three strong inflow days earlier in the week. But the reversal wiped out most of those gains.

So what spooked investors? According to Decrypt, analysts point to a familiar cocktail of macro fears: renewed U.S.-Iran tensions, rising oil prices, inflation worries, and growing expectations that the Federal Reserve could raise interest rates later this year. When geopolitics and monetary policy both look dicey, risk assets like Bitcoin tend to be the first thing institutions sell.

HashKey Research noted that the heavy selling in IBIT suggests institutions are actively reducing short-term Bitcoin exposure rather than building long-term positions. But not everyone is bearish. Grayscale argues that Bitcoin may have already found its bottom if the Fed refrains from additional rate hikes, and some market participants expect ETF inflows to recover if geopolitical tensions ease.

With the Fed's July 29 policy decision just around the corner, macro developments are likely to remain the biggest driver of Bitcoin ETF flows in the near term. For now, it's a waiting game.