Asset managers BlackRock and Grayscale have significantly increased their holdings of Bitcoin through their U.S. spot Bitcoin ETFs. As of recent data, these ETFs collectively hold almost 3% of Bitcoin's circulating supply.

BlackRock's iShares Bitcoin Trust (IBIT) currently holds 357,736.76150 BTC, while Grayscale's GBTC holds 227,712.3295 BTC. Combined, they account for 2.97% of Bitcoin's total supply. Additionally, Grayscale has further Bitcoin holdings in its Digital Large Cap Fund and Grayscale Bitcoin Mini Trust.

U.S. spot Bitcoin ETFs have experienced a surge in inflows over the past week, totaling $543 million. This positive trend is attributed to hints from Federal Reserve Chair Jerome Powell regarding a potential interest rate cut.

CoinShares analyst James Butterfill noted that the majority of inflows occurred on Friday following Powell's dovish comments, highlighting Bitcoin's sensitivity to interest rate expectations. Powell's remarks at the Jackson Hole Economic Policy Symposium indicated that interest rate cuts are likely to occur soon, based on economic data and evolving conditions.

In response to Powell's comments, Bitcoin's price surged to levels above $64,000. While it has since pulled back slightly to around $62,300, it remains up for the week.