Interactive Brokers as custodian — what actually protects a non-US client's securities
Data as of 24 Sep 2026.
Verdict: trustworthy. A broker with $22.3bn of equity has twice covered client losses out of its own pocket, and US law requires client securities to be segregated from the firm's own. The weak spot isn't the broker's solvency. The excess-SIPC insurance covers almost nothing in a mass failure, and in a margin account the broker can use part of a client's securities. Fully paid securities with no margin debt are the best-protected category.
What it is
Interactive Brokers Group (NASDAQ: IBKR) is one of the largest electronic brokers in the world: 5.19m accounts and $930.3bn in client equity (Q2 2026). Clients outside the US are onboarded through regional entities — IB UK, IB Ireland, IB Central Europe, IB Hong Kong, IB Singapore, IB Australia, IB Japan and others; some of these are only authorised to introduce clients and arrange deals and custody. Which entity carries a client's securities depends on where the account is opened, and that decides the protection scheme: accounts carried by the US entity, Interactive Brokers LLC, fall under SIPC; accounts carried by an EU, UK, Asian or Australian entity fall under that jurisdiction's own investor-compensation rules, each with its own limit and scope. The findings below cover the US entity, which is the group's main broker-dealer.
Sources: Q2 2026 earnings call transcript, 21 Jul 2026
Findings
1. The capital base is large and growing
Group equity is $22.3bn (+20% YoY). Excess regulatory capital after all buffers is around $10.3bn, up $1.1bn on the quarter (Q2 2026 results, 21 Jul 2026). The firm absorbed the two worst losses in its history itself. On 15 Jan 2015, when the SNB dropped the EUR/CHF floor, negative client equity came to ~$120m (under 2.5% of capital at the time). On 20 Apr 2020, when WTI went negative, the broker compensated clients ~$104m. Neither loss was pushed onto other clients.
Sources: Q2 2026 transcript · Q2 2026 press release (Business Wire) · LeapRate, Jan 2015 · Finance Magnates, 2020
2. The insurance is per account, not for a broker collapse
Securities at IB LLC are covered by SIPC up to $500,000 per account, including up to $250,000 in cash. Above that sits a Lloyd's policy: up to a further $30m per account (cash up to $900,000), but subject to a $150m aggregate limit across all clients. Against $930.3bn of client equity, that's 0.016%. If the broker failed with a shortfall affecting many clients at once, the policy would cover a rounding error.
The real protection is SEC Rule 15c3-3: the broker must hold clients' fully paid securities separately from its own and cannot use them. Client cash goes into a dedicated reserve that, since 2025, is computed daily.
Sources: IBKR, "Client Protection" (text via search results — the page returns 403) · Sidley, Jan 2025 (daily reserve computation)
3. Margin accounts: the broker can use part of the client's securities
Under the same Rule 15c3-3, the broker may rehypothecate a client's margin securities up to 140% of that client's debit balance. No debit, no rehypothecation — everything stays segregated. With a debit, securities worth up to 140% of it can end up elsewhere, and in a failure that portion comes back on worse terms than fully paid stock. Separately, lending out fully paid securities (Stock Yield Enhancement) is opt-in only. How lent securities are protected if the broker fails was not verified here — until it is, the programme adds an unpriced risk to what is otherwise the best-protected category.
Sources: FINRA, SEA Rule 15c3-3 Interpretations · Databento, "What is rehypothecation"
4. Regulatory record: a sanctions fine, unrelated to custody
On 15 Jul 2025 IB LLC agreed to pay OFAC $11.8m over 12,367 sanctions violations (2016–2024) involving clients in Iran, Cuba, Syria and Crimea, caused by geo-blocking and screening failures. It has nothing to do with safekeeping of client assets. It does mean screening is now stricter, and an account can be frozen while a sanctions review runs.
Sources: Compliance Week · JD Supra / Volkov Law
5. Not about the broker, but about US securities: estate tax
For a non-US person, US stocks and US-domiciled funds are U.S.-situated assets. If their value at death exceeds $60,000, a US federal estate tax filing obligation arises. That's true at any broker, so it has no bearing on IBKR's safety. But for a non-US investor choosing between a US-domiciled fund and an equivalent fund domiciled outside the US, it's a material difference worth checking against their own tax situation.
Source: IRS, updated 27 Jun 2026
What breaks it, and at what number
| Event | What's lost | How plausible |
|---|---|---|
| IB LLC bankruptcy with a securities shortfall | the share of the shortfall above SIPC's $500,000; the Lloyd's policy is $150m for everyone | very low: $10.3bn excess capital, daily reserve |
| Bankruptcy with segregation intact | nothing in value; months without access while accounts are transferred to another broker | very low; the cost is time |
| Margin debit plus broker failure | securities up to 140% of the debit, rehypothecated, come back on worse terms | only with a debit balance |
| Account frozen by a sanctions or AML review | access for the duration of the review | depends on the client, not the broker |
Unknowns
- Which entity carries a given account — IB LLC or a regional entity. It shows on the statement in the carrying-broker field, and it decides whether SIPC applies or a local scheme (each regional scheme has its own limit and covers its own set of clients).
- The primary text of IBKR's client-protection page and press release: both return 403, so figures come from secondary text rather than the pages themselves.
- Unknown to anyone: how quickly non-resident accounts would actually be transferred if IB LLC failed. There's no precedent for a broker failure of this size.
What pulls the verdict
Any one of these: a quarterly report showing group equity below $15bn or excess regulatory capital below $5bn (half today's level) · SEC or FINRA charging IB LLC with a Rule 15c3-3 customer-protection violation · accounts moved to a non-SIPC entity without client consent · the broker passing a third party's default loss on to other clients.
Next checkpoint: the Q3 2026 report (October 2026) — equity and excess capital against the thresholds above. Quarterly after that.
The call
In the Q3 2026 report, group equity will be no lower than $22.3bn and excess regulatory capital no lower than $10bn (basis: +20% equity YoY; the largest historical losses were under 2.5% of capital).
Research for information only. Not investment advice.