As Bitcoin's price surged past $66,000, a notable increase in inflows was observed in U.S. spot Bitcoin ETFs. This surge marked a two-week high, with a total of $303 million flowing into these ETFs. According to data published by Farside Investors, all spot Bitcoin ETFs except for BlackRock's iShares Bitcoin Trust (IBIT) saw inflows on May 15.

Interestingly, IBIT remained stagnant for the third consecutive day, neither experiencing significant inflows nor outflows. Fidelity's FBTC led the charge with a substantial influx of $131.3 million, while Grayscale's GBTC marked its first day of inflows in a week, attracting $27 million.

The excitement surrounding these inflows was palpable, with Sunnydecree, a Bitcoin investor/analyst, noting, " $303'000'000 Bitcoin ETF inflows yesterday. We are so back!" Another user, 'Bitcoin for Freedom', added, "That's a Bull Market Multiple of 276 No one is ready for this bullrun. We've seen nothing yet!"

However, the story doesn't end here. According to 13F filings, international hedge fund Millennium Management has reported holding nearly $2 billion in spot Bitcoin ETF shares. As of March 31, Millennium had a total of $1.94 billion invested across five spot Bitcoin ETFs, including ARK 21Shares, Bitwise, Grayscale, iShares, and Fidelity's offerings. BlackRock's Bitcoin fund represents the hedge fund's largest allocation, with over $844 million invested, followed closely by Fidelity's fund with just over $806 million in shares held.

Eric Balchunas, a Bloomberg ETF analyst, noted, "It's only retail traders buying the #bitcoin ETFs." James Seyffart added, "It's only retail traders buying the #bitcoin ETFs." Joining the critics of ETFs, Salim Ramji, the newly appointed CEO of Vanguard, stood firm on the company's decision not to pursue a spot Bitcoin ETF launch.

Despite criticism, institutional investors and banking giants are flocking towards Bitcoin investments. According to the latest SEC filings, Bracebridge Capital disclosed a $363 million investment in spot Bitcoin ETFs, while J.P. Morgan's clients contributed $731,246 to the same. Galaxy Digital Holdings Ltd. also made waves with a remarkable 40% hike in net income to $422 million, attributed to the influence of spot Bitcoin ETFs.

These recent resurgences in spot Bitcoin ETF investments might have been the biggest factors behind Bitcoin's hike this week.