Bitcoin ETFs Analysis Week 37 2025

Situation Summary

After a strong withdrawal period in early September, week 37 saw a clear recovery in capital flows into Bitcoin ETFs in the US. The highlight was September 11 , when total net capital flows reached $552.78 million , the highest level since late July. Of which, BlackRock iShares Bitcoin Trust (IBIT) led with $366.2 million , followed by Fidelity Wise Origin Bitcoin Fund (FBTC) with $134.7 million , and Bitwise BITB attracted an additional $40.4 million .

As of September 13, total weekly net inflows into Bitcoin ETFs exceeded $1.2 billion , with at least four out of five trading sessions reporting positive inflows. Fidelity and BlackRock continued to be the main drivers of inflows, while smaller funds such as Ark 21Shares (ARKB) and VanEck (HODL) also contributed significantly.

However, not all is positive. Some small funds still witnessed capital withdrawal sessions, typically some slightly negative flows at the beginning of the week (on September 9, some non-top funds recorded net capital withdrawals). However, this did not greatly affect the general trend when positive capital flows from large funds were overwhelming.

The total assets (AUM) held by these funds has reached $150.31 billion , equivalent to about 1.3 million BTC . This is a record number, reflecting the growing role of ETFs in legitimizing institutional capital flows and affirming Bitcoin's position in the traditional financial market.

Bitcoin ETFs Cash Flow

Throughout the past week, the positive net cash flow into ETFs has been very positive, with the largest buying force coming from iShares Bitcoin Trust (IBIT) and Fidelity Bitcoin Fund (FBTC). However, in the middle of the week, FBTC sold a small amount of BTC and recorded the only negative cash flow of the week.

Total US Bitcoin ETFs data for the past week:

• IBIT recorded +1.037 billion USD

• FBTC records +850 million USD

• GBTC records +13 million USD

• ARKB records +182 million USD

• BITB records +112 million USD

• BITCO records +12 million USD

• EZBC records +13 million USD

• BRRR does not trade this week

• HODL recorded +43 million USD

• BTCW does not trade during the week

The total inflow of Bitcoin ETFs in the US last week was about 2.262 billion USD, strong buying power appeared from IBIT and FBTC, recording over 800 million USD for each side, followed by ARKB and BITB both recording positive inflows of over 100 million USD flowing into the treasury. Notably, in the first 2 weeks of September, IBIT only sold 63.2 million USD and did not record any negative inflows. On the other side, FBTC sold more than 160 million USD during the first 2 weeks of September.

Despite the strong buying pressure, there are still some funds that have gone against the trend created by IBIT, on September 9, 3 funds confirmed negative cash flow of more than 130 million USD. When comparing the BOT buying and selling balance of ~ 17 (very high ratio), this clearly reflects the confidence and expectation of the growth value of the portfolio they are investing in. Bitcoin is encouraged to maintain above the $ 104,000 price range and has not been able to move to a lower range.

BlackRick and Fidelity’s recent reports are now maintaining 70% of the total positive flows across the ETF industry, and they have pushed their low fee strategy (0.25%) to increase liquidity and investor confidence. Recent news shows that Grayscale is continuing to lose market share due to higher fees and less competition.

For small funds like ARKB and BITB, although the capital flow is smaller than the two big guys above, it is still stable and reflects the group of investors who prefer diversification and thematic funds (especially Cathie Wood's ARK which often attracts retail money). Other funds like BTCO, EZBC, BRRR, BTCW have market share that is being "strongly eroded" and have poor liquidity.

Personal perspective

While recent inflows have been positive for the Bitcoin ETF market, the overall picture still reflects a clear divide among major funds. Some names like Fidelity and Bitwise are seeing new investor interest, while “big guys” like BlackRock’s IBIT and Grayscale’s GBTC are still struggling to cope with capital withdrawal pressure.

With Bitcoin prices remaining stable and trading liquidity increasing, the next few weeks will be crucial in determining whether the current inflows are the start of a sustained recovery trend or just a short-term reaction to recent price volatility. In particular, the strong entry of institutions and the growing role of investment advisors could be decisive factors in determining the future shape of the Bitcoin ETF market.

Amount of Bitcoin ETFs are holding

In the current picture of the Bitcoin ETF market in the US, the near-absolute dominance of BlackRock's IBIT is the most prominent. With holdings many times larger than its competitors, IBIT has become the liquidity center of the entire market, creating a strong network effect: the more concentrated the flow of money, the lower the transaction costs, thereby attracting more investors.

Fidelity's FBTC holds the second spot, leveraging its in-house distribution ecosystem to maintain steady traction. In contrast, Grayscale's GBTC – while still large – is losing ground as it faces prolonged outflows due to high fees and a shift in investor sentiment toward newer, more efficient funds.

The capital flows in recent weeks clearly reflect the divergence in which IBIT and FBTC attract billions of dollars in inflow, while small funds such as ARKB or BITB only maintain modest growth, mainly thanks to their brands or specialized investor groups. Smaller funds are almost "out of the game" when they cannot achieve enough liquidity to attract institutional investors. This is the picture of market share according to the "law of power" - two poles dominate, the rest are pushed aside.

From a supply-demand perspective, the weekly net inflows of major ETFs now far exceed the new issuance from miners after the halving, meaning these funds are directly absorbing the majority of the new supply of Bitcoin. As prices remain stable and liquidity increases, ETF inflows become a fundamental driver of the market, especially as institutions and investment advisors increasingly proactively allocate Bitcoin as part of their long-term portfolios.

However, the current market structure also poses systemic risks. The concentration of a few leading funds means that any macro shock – such as a sharp rise in US dollar yields or a liquidity shock – could trigger a massive outflow, rapidly depleting spot market liquidity. This is a pro-cyclical risk, as ETFs are a price booster in good times; but when things go wrong, they can act as a catalyst for volatility.

Investment capital to market capitalization ratio

The chart showing the ratio of AUM (Assets Under Management) to Market Cap shows that the level of “ETFization” of Bitcoin is approaching a very high threshold. Most large funds such as IBIT, FBTC or GBTC have AUM ratios that are almost asymptotic to the capitalization they represent, reflecting the ability to attract strong capital from institutional investors. This is a clear sign that ETFs have become the main door for traditional money to access Bitcoin.

BlackRock's IBIT holds an overwhelming position, with an almost absolute AUM ratio compared to its capitalization. Fidelity's FBTC, although slightly lower, still maintains a level above 90%, enough to affirm its role as the number two fund in the market. GBTC , despite recent capital withdrawal pressure, still shows that its asset management scale is still very large, continuing to be one of the three main pillars of the Bitcoin ETF segment. Smaller funds such as BITB or HODL have modest sizes, but in their segments, they also have a near-saturated AUM/Market Cap ratio.

The market capitalization of funds in September generally tended to decrease slightly compared to previous months, specifically large funds IBIT, FBTC, and GBTC by about 3-5% although the recovery of Bitcoin price showed that fund capitalization did not increase correspondingly with Bitcoin price.

This is due to the funds recording net capital withdrawals, causing the total amount of BTC held to decrease, even though the BTC price in the period of August 18-22 increased again. However, large investment funds IBIT ($80.72 billion) and FBTC ($21.42 billion) still maintained a solid position, helping the total capitalization not fluctuate too much. And when entering week 35 (August 25-29), the cash flow trend reversed when Bitcoin ETFs recorded a positive net capital flow of +440 million USD and week 36 continued to be positive by 250 million USD, showing that demand has returned to the leading fund group. However, the market capitalization of funds has not recovered strongly because the Bitcoin price in the same period decreased to around 108K-110K USD. Compared to week 36 (+250 million USD), week 37 has broken out strongly, reflecting a clear reversal in investor sentiment.

Notably, the divergence between BTC price and AUM shows that institutional money has not really agreed with the price increase. If this trend continues, it is likely that ETF investors are taking advantage of the recovery to take short-term profits , instead of expanding long-term positions.

It should also be noted that the slight decline in Bitcoin ETF AUM in August may not be entirely due to BTC factors, but partly due to capital shifting to Ethereum ETF products (recent news). This shift not only shows caution in the macro context, but also suggests the possibility that capital is reallocating to Ethereum or other investment channels.

Stock Price Volatility and Bitcoin Holding Profits

Average August and early September . Most funds increased steadily around 7 - 10%. The most notable is HODL, which only increased slightly by about 2% in week 34 but decreased by more than 5% in week 35. On the other hand, EZBC is the only fund that decreased by 1.98% . Some funds with defensive strategies such as HODL, which are less affected by general market fluctuations. Overall, the average price in September shows a positive recovery for most Bitcoin ETFs, although there is still a differentiation between large funds and defensive funds.

While most major Bitcoin ETFs such as IBIT, GBTC, and FBTC maintain stable holdings around ~2% market share, the return performance of BTC holdings varies significantly. IBIT , despite being the largest fund, recorded a slightly negative return on BTC under management – ​​reflecting recent cost pressures or suboptimal timing of disbursements. In contrast, GBTC and FBTC still maintain positive returns, but still quite modest, just under 1%.

The picture changes significantly in the group of medium and small-sized funds. BITB stands out when the profit rate from BTC holdings exceeds 3%, the highest in the group, showing that the timely disbursement strategy has helped this fund outperform the rest. HODL, AZBC and BTCO are also benefiting significantly, with profit rates ranging from ~2.2% to 2.5%, proving the attractiveness of capital allocation during market corrections. Notably, BRRR also achieved a profit rate of over 3%, equal to BITB, showing that despite its small scale, it has good market-keeping ability.

Overall, the new data shows that small funds are outperforming their larger peers . This reflects the flexibility of their investment strategies and their greater risk tolerance, as opposed to larger players like IBIT, which tend to be more stable but are susceptible to the massive inflows and cyclical nature of institutional investors.

News related to BTC ETFs

CoinShares Weekly Report (August 19, 2025) recorded Bitcoin ETF outflows of -1.175 million USD, the largest in 6 months, due to investors taking profits after the peak of 124k USD and concerns about the US economic recession. And Research also emphasized "cautious sentiment before the Fed's Jackson Hole symposium", predicting that interest rates may not decrease as quickly as expected, leading to capital withdrawals from risky assets such as Bitcoin ETF.

BlackRock Analysis (August 20, 2025) warns of "rotation to Ethereum ETF" with inflows of +$2.9 billion in the week, as staking yields (3-5%) are more attractive than Bitcoin. This report greatly affects the outflows of IBIT, BlackRock's main fund, as investors shift capital to ETHA.

The Block Research (04/09/2025) Cumulative inflows into BTC ETFs in the first two days of the week reached over +633 million USD , the highest since early August. The leading fund was IBIT with +350 million USD. The Block emphasized that this trend reflects long-term confidence, as most of the inflows come from pension funds and large institutions.

Bloomberg Intelligence (03/09/2025) analyzed the flow of ETFs, showing a clear reversal from Ethereum to Bitcoin . While Ethereum ETFs lost about -135 million USD, Bitcoin ETFs net absorbed more than +300 million USD. This shows that investors are prioritizing BTC as a safe haven asset, especially ahead of the weaker-than-expected US economic report.

CryptoSlate (September 12, 2025) shows that while Bitcoin ETFs attracted a net of $2 billion in September, Ethereum ETFs were withdrawn by about $550 million . This trend shows a preference for BTC over ETH in a context of macroeconomic instability.

Decrypt (12/9/2025) emphasized the shift of money flow from Ethereum to Bitcoin, with institutional investors considering BTC as a safe haven asset. This is a signal to strengthen Bitcoin's recovery momentum, especially when the price surpassed the $ 114,000 threshold this week.

Comments and Conclusions from HCCVenture

Overall, the US Bitcoin ETFs cash flow has grown steadily over the past week and has maintained a positive cash flow since the beginning of September. BlackRock is currently still showing their position and cash flow strength, continuously collecting Bitcoin into the treasury with the total amount of Bitcoin soon reaching 1 million BTC.

The capital flow of more than 2 billion USD ensures that BTC cannot correct further at the current price range, the sign of the purchasing power of ETFs comes from the stock profit maintained above 2.5%/share, showing that they are still highly expected by investors and shareholders. With increased confidence and strong capital flow, Bitcoin will be able to break out to a higher price range and achieve the great profit expectations they are setting.

While recent inflows are a positive sign for Bitcoin ETFs, the mixed performance of major funds suggests that the market remains divided. Some funds, like Fidelity and Bitwise, are seeing renewed investor interest, while others, like BlackRock’s IBIT and Grayscale’s GBTC, continue to struggle with outflows. As Bitcoin prices stabilize and trading volumes increase, the next few weeks will be critical in determining whether the inflows represent a sustained recovery or a temporary reaction to recent price volatility. Institutional interest, particularly from investment advisors, could play a key role in shaping the future of Bitcoin ETFs.

Disclaimer: The information presented in this article is the author's personal opinion on the cryptocurrency field. It is not intended to be financial or investment advice. Any investment decision should be based on careful consideration of your personal portfolio and risk tolerance. The views expressed in the article do not represent the official position of the platform. We recommend that readers conduct their own research and consult with a professional before making any investment decisions.

Compiled and analyzed by HCCVenture

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