FBTC vs ARKB
FBTC and ARKB are two of the most popular spot Bitcoin ETFs for long-term investors — particularly those using tax-advantaged retirement accounts. Both launched in January 2024, both charge well below the category average, and both have established themselves as credible alternatives to the dominant IBIT.
The differences between them are subtle but meaningful for the right investor: custody structure, fee savings, and brokerage integration. For investors choosing a Bitcoin ETF to hold inside an IRA for years or decades, this is the comparison that matters most.
Side-by-Side Comparison
| Metric | FBTC | ARKB |
|---|---|---|
| Fund Name | Fidelity Wise Origin Bitcoin Fund | ARK 21Shares Bitcoin ETF |
| Issuer | Fidelity | ARK/21Shares |
| Expense Ratio | 0.25% | 0.21% |
| BTC per Share | ... | ... |
| Shares per 1 BTC | ... | ... |
| Launch Date | Jan 11, 2024 | Jan 11, 2024 |
| Custodian | Fidelity Digital Assets | Coinbase Custody |
| Options Available | Yes | Yes |
Key Differences
The most meaningful distinction between FBTC and ARKB is custody. FBTC is the only major spot Bitcoin ETF that self-custodies through Fidelity Digital Assets — Fidelity's own regulated custodial affiliate. ARKB uses Coinbase Custody, like nine of the twelve spot Bitcoin ETFs. For investors concerned about Coinbase concentration across the industry, FBTC offers genuine structural diversification at the operational level.
Fees slightly favor ARKB: 0.21% versus FBTC's 0.25%. That 4-basis-point difference compounds over decades in a retirement account. On a $50,000 IRA position over 20 years assuming 15% annualized Bitcoin returns, the fee difference amounts to roughly $3,000 — real money, though modest relative to the total return.
Brokerage integration is where FBTC shines for a specific audience. If you hold a Fidelity IRA, 401(k), or brokerage account, FBTC integrates seamlessly into your existing platform. There is operational simplicity in having your Bitcoin ETF at the same institution that manages your other investments. ARKB offers no similar platform advantage — it trades on any brokerage but has no special integration anywhere.
Fund size favors FBTC significantly: roughly $13.5 billion versus ARKB's approximately $2.5 billion. This translates to tighter bid-ask spreads and more trading depth for FBTC, though ARKB has adequate liquidity for typical retail transactions.
Use our calculator to compare directly.
Which Is Better for an IRA?
Inside a tax-advantaged account, the calculus simplifies. Wash sale rules and short-term capital gains are irrelevant. The decision comes down to fees, custody preference, and brokerage integration.
If you use Fidelity for retirement accounts, FBTC is the natural choice — seamless integration, proprietary custody, and sufficient liquidity. The 4-basis-point fee premium over ARKB is a reasonable price for custody diversification and platform convenience.
If you prioritize minimizing fees above all else and have no brokerage preference, ARKB's 0.21% expense ratio makes it the leaner choice. Over very long time horizons in a tax-advantaged account, even small fee differences compound meaningfully.
Either is an excellent choice for long-term, retirement-focused Bitcoin exposure.
ARKB's 4-basis-point fee advantage is modest but real over long holding periods. The calculator below shows how this difference compounds for your specific investment amount and horizon.
Fee Savings Calculator
Strike Price Comparison
Different ETFs have different BTC-per-share ratios, so the same strike price implies different Bitcoin prices.
The Bottom Line
FBTC and ARKB are both excellent choices for long-term Bitcoin ETF investors. FBTC wins on custody diversification, fund size, and Fidelity platform integration. ARKB wins on fees by a small margin. For Fidelity IRA holders, FBTC is the clear choice. For cost-minimizers without brokerage preference, ARKB offers slightly leaner economics.
They also form a natural pair for investors who hold Bitcoin ETFs across multiple accounts — FBTC in your Fidelity IRA, ARKB in a taxable brokerage, for example — providing both custodial diversification and portfolio flexibility.
For the full landscape including all twelve spot Bitcoin ETFs, see our Best Bitcoin ETF in 2026 guide. Convert shares to Bitcoin with our calculator.
See our tax-loss harvesting guide for details on this strategy.
Looking beyond these two? See our full comparison of all 12 spot Bitcoin ETFs.
Convert FBTC or ARKB shares to Bitcoin → calculator
More Comparisons
Frequently Asked Questions
Should I pick FBTC or ARKB for my IRA?
If your IRA is at Fidelity, FBTC offers seamless integration and self-custody through Fidelity Digital Assets. If your IRA is elsewhere and you want the lowest fee, ARKB at 0.21% saves 4 basis points annually versus FBTC's 0.25%. Both are strong choices.
Does FBTC have a different custodian than ARKB?
Yes. FBTC self-custodies through Fidelity Digital Assets — Fidelity's own regulated custodial affiliate. ARKB uses Coinbase Custody. FBTC is the only major spot Bitcoin ETF that does not rely on Coinbase or a third-party custodian.
Is the fee difference between FBTC and ARKB significant?
Over short periods, no — 4 basis points on $10,000 is roughly $4 per year. Over decades in a retirement account, it compounds to a more meaningful amount.
This article is for informational and educational purposes only and does not constitute investment, legal, or tax advice. Bitcoin and Bitcoin-related products are highly volatile and involve substantial risk of loss. Tax treatment of Bitcoin ETFs — particularly regarding wash sale rules — remains an area without explicit IRS guidance. Consult qualified professionals regarding your specific situation before making investment decisions. Past performance does not guarantee future results.