BlackRock’s IBIT vs Fidelity’s FBTC comparison

Concentration in the largest wrappers

U.S. spot bitcoin ETFs recorded $176.0 million in net inflows on Tuesday, October 27. BlackRock’s iShares Bitcoin Trust took in $151.5 million of this total. Fidelity’s Wise Origin Bitcoin Fund added $24.5 million. These two funds drew all the flows for the session. The other ten funds, including Grayscale’s GBTC, recorded no net flow. No spot bitcoin ETF posted an outflow on October 27. This two-day rebound follows losses of $635.5 million on October 22 and $137.9 million on October 23. The concentration of inflows in the two largest, most liquid wrappers suggests that allocators and advisers use IBIT and FBTC as default access vehicles while smaller products remain largely idle on most days. This pattern mirrors the massive flow concentration seen in August 2026. During the week of August 3, U.S. spot bitcoin ETFs pulled in $853.54 million in net inflows. BlackRock’s IBIT accounted for approximately $693 million of that total. IBIT captured 81 cents of every dollar entering the category during that period. The August reversal remains fragile. In the week following the August 7 peak, the category reversed with roughly $390 million in outflows across four of five sessions.

Scale and liquidity advantages

IBIT holds significantly more assets than FBTC. On September 24, 2026, IBIT held roughly $67.9 billion in assets. FBTC held $15.3 billion on that same date. This makes IBIT’s asset base about 4.4 times larger than FBTC’s. IBIT also trades about 10 times the dollar volume of FBTC. On September 24, 2026, IBIT’s average daily volume reached approximately $1.8 billion in notional value. In contrast, FBTC’s average daily volume reached approximately $0.18 billion. You should recognize that size and volume dictate the institutional preference. Both funds charge an expense ratio of 0.25%. Both funds also saw their initial fee waivers expire. IBIT had a waiver of 0.12% on its first $5.0 billion of assets for the twelve months starting from 11 January 2024. FBTC charged 0% from its launch until 31 July 2024.

Custody diversification options

The structural difference between the two funds is custody. Most products in this category use Coinbase Custody. IBIT uses Coinbase Custody Trust and Anchorage Digital Bank. FBTC does not use Coinbase at all. Fidelity keeps its bitcoin through Fidelity Digital Assets, N.A. This makes FBTC the only mainstream fund without Coinbase custody. IBIT and FBTC provide identical exposure to bitcoin. Some investors pick IBIT because they already work with BlackRock or iShares. Other investors pick FBTC because they want custody outside of Coinbase. Some investors want two positions with the same fee and the same exposure to switch between for tax-loss harvesting. When you switch, you must match dollar amounts rather than share counts because an FBTC share costs roughly 1.5 times an IBIT share. The market has moved away from the model of one custodian per fund. For example, Valkyrie’s BRRR uses Coinbase, BitGo, and Komainu, while ARKB names four different custodians.

Price pressure and the cost basis

The aggregate cost basis for U.S. spot Bitcoin ETF holdings sits around $90,200 per coin. At a price of $64,722, the aggregate ETF holder is underwater by approximately 28.2%. This price gap creates mechanical pressure. When Bitcoin prices move toward the top of the range, redemptions offer opportunities for holders who allocated at higher prices. In 2026, the complex saw significant declines. Spot Bitcoin ETFs recorded $5.4 billion in net outflows during the first half of 2026. June 2026 alone removed $4.51 billion from the category. One eight-week stretch saw $8.26 billion withdrawn. The longest outflow streak ran 13 sessions from May 15 to June 3, shedding $4.37 billion. IBIT’s direction determines the category’s direction because nothing else has the scale to offset it. The $9 billion gap between IBIT’s cumulative inflows and the total category inflows shows that every other fund is net negative on a cumulative basis. Will the current rebound offset the massive outflows from earlier in the year?