Interactive Brokers' securities-lending income: why $65m and $427m describe different measures

Interactive Brokers estimated that securities-lending activities generated $427 million of net interest in the third quarter of 2026, up from $314 million a year earlier. Yet the line labelled securities borrowed and loaned in its operating interest analysis fell from $133 million to $65 million. Both figures appear in the same quarterly filing. They measure different parts of the financing operation: the broader estimate attributes cash-collateral interest to securities lending even when that income sits in other rows of the table.[1]

The difference between the two presentations was $362 million in the September 2026 quarter, twice the $181 million difference a year earlier. Reassigning the interest changes the apparent direction of the securities-lending business but does not change group income. A separate reconciliation is also necessary: the operating interest analysis totals $1.191 billion, whereas the income statement records $1.154 billion of GAAP net interest income. Treating those totals as interchangeable would introduce another $37 million classification error.[1]

These distinctions matter for investors trying to separate a broker's commissions, margin lending, customer-cash income and securities financing. The same collateral can connect several activities. An activity-based estimate can help explain their economics, but it must replace the relevant classification amounts in an analytical model, rather than being added to them as extra revenue.[1]

Two reconciliations, with different purposes

The operating analysis lists $815 million related to segregated cash and securities, $1.114 billion from margin loans, $65 million from borrowed and loaned securities, negative $1.028 billion on customer credit balances and $225 million of other net interest. Those amounts total $1.191 billion. Its footnote explains that the analysis includes instruments with characteristics of interest whose income is booked elsewhere in the financial statements: $11 million in other fees and services and $26 million in other income. Subtracting those $37 million reconciles the table to GAAP net interest income of $1.154 billion.[1]

The arithmetic is straightforward. For 2026, subtract the reported $65 million loaned-and-borrowed line from the activity estimate of $427 million: $362 million. For 2025, subtract $133 million from $314 million: $181 million. The gap widened by $181 million, but that gap represents interest reattribution under management's disclosed alternative view, not an addition to GAAP revenue. In percentage terms, the narrow line declined by $68 million, or 51.1%, while the broader activity estimate gained $113 million, or 36.0%. These two percentage changes are not rivals in a dispute about the same accounting measurement. They answer different questions.[1]

Interactive Brokers explicitly describes the adjustment as an estimate. It does not provide a public transaction-by-transaction ledger allowing an outside reader to reconstruct every dollar of collateral interest from first principles, nor does it divide the $362 million between the two originating reported rows in the section used for this comparison. The reconciliation here is consequently the difference between disclosed measures, not an independently audited reconstruction of thousands of loan transactions. The $427 million estimate cannot replace the $65 million operating-table line, because they measure different allocations of interest. Equally, the narrower line does not capture the company's full estimate of the activity's financing economics.[1]

For the 2025 comparison, the operating table totals $999 million and includes $10 million in other fees and services and $22 million in other income. Removing those $32 million gives GAAP net interest income of $967 million. The operating total therefore grew $192 million, or 19.2%; GAAP net interest income grew $187 million, or 19.3%. Neither increase is the $362 million securities-lending reallocation. The first bridge separates accounting captions; the second attributes financing economics within the operating analysis.[1]

The balance-sheet activity behind the estimate

Average securities loaned reached $36.203 billion during the third quarter, versus $20.691 billion a year earlier. That is an increase of $15.512 billion, approximately 75.0%. Average securities borrowed rose from $9.037 billion to $12.290 billion, a 36.0% increase. The two categories have different directions and legal functions in the financing chain and must not be netted mechanically to create a free-cash figure. An increase in securities on loan, however, provides a plausible operating context for an increase in gross lending-related income even when the narrow presentation line weakens.[1]

The same filing shows average customer margin loans rising from $70.805 billion to $104.032 billion, up 46.9%, while average customer credit balances rose from $141.763 billion to $176.566 billion, up 24.5%. Segregated cash and securities averaged $95.092 billion versus $81.906 billion. Taken together, the movements show a broker intermediating larger amounts on both sides of client portfolios. They do not establish the net contribution of any single new customer, stock, regional legal entity or particular lending strategy. Nor can the average balances be equated with quarter-end custody assets, which are measured at a different point in time.[1]

The interest table supports a useful stress test of the simplistic assertion that more lending volume always increases the displayed securities-lending interest row. Here, average securities loaned increased 75%, the wider estimated net-interest contribution increased 36%, and the displayed $65 million row decreased 51%. This is direct evidence that the three measures respond to different mixes of rate, collateral and accounting classification. It is not evidence that the broker received an undisclosed windfall. A valid profitability assessment must identify the economic numerator, the relevant balances, the collateral remuneration and the costs allocated to the service.[1]

The group reports a wider interest-rate compression in the quarter. The annualised yield on segregated cash and securities declined from 3.81% to 3.40%; margin loan yields fell from 4.60% to 4.25%; and the annualised rate paid on customer-credit balances fell from 2.64% to 2.31%. Such changes are consistent with lower rates affecting both earned and paid interest. They do not reveal the average fee rate for every loaned stock, which varies with its borrow scarcity, collateral convention and securities-lending market conditions. Treating the $427 million activity estimate as a pure per-share loan fee would be wrong.[1]

What the customer stock-yield programme actually says

Interactive Brokers describes a Stock Yield Enhancement Program under which eligible customers holding fully paid shares can permit the broker to lend them. Its published quarterly discussion states that the rebate paid to the participating customer is generally equal to 50% of a market-based rate for lending those shares. The phrase generally matters: it does not promise that every security will be borrowed, that every possible borrowing fee is constant, or that a particular customer's realised income will mirror a quarterly group growth percentage. A lending arrangement must also be distinguished from a broker's ability to finance margin positions using collateral in other permitted circumstances.[1]

The filing describes cash and/or US Treasury securities placed as collateral securing the loan in the customer's account, with the assets held in segregated accounts or by an affiliate acting as collateral agent for the customer. That mechanism is a description of the programme's protection arrangement, not a guarantee against every possible counterparty, operational or market event. The adequacy of collateral depends on contractual, valuation and operational processes, while the programme's customer entitlements depend on the account agreement. An outside reader cannot infer from these aggregate figures how much collateral was posted for a particular account or whether a given stock was ever lent.[1]

One operationally important difference is between the broker's economic estimate and the payout to customers. The company-wide $427 million figure covers securities-lending net-interest economics under management's alternative presentation, not the distributable pool under its fully-paid stock programme. The programme's participant shares and any additional revenues attributable to other securities-financing arrangements are not individually isolated by that single number. Consequently, dividing $427 million by a published retail client count to produce an implied stock-lending payment per investor would be unsound. The denominator would contain many customers who may not have participated or held borrowable securities.[1]

The proper comparison for a customer is instrument-specific: whether the shares were lent, the collateral and fee arrangements, the days outstanding, the lending rate, and the share of the rate the customer actually receives. Customers also need to understand how the terms affect recall, sale proceeds and the status of lending arrangements at the time of an account event. The quarterly financial statements cannot replace the client's contractual records or activity report. They establish the scale of group lending economics and the accounting link, not a promised individual return.[1]

Why this changes analysis of a listed brokerage

A listed broker earns money from multiple intertwined activities: commissions, customer cash, margin lending, securities financing, exchange and market-data services. Interactive Brokers' earnings release reported third-quarter net revenue of approximately $1.91 billion under GAAP, but a single classification in its net-interest table does not define the securities-lending part of those consolidated earnings. Analysts separating the group into business lines must avoid counting collateral interest twice while also avoiding the opposite mistake of omitting activity economics because they are recorded in another row.[1][2]

For a valuation model, two approaches could be defensible provided they are not mixed. A presentation-led model could preserve reported interest line items and analyse margin balances, securities lending and customer credits together. An activity-led model could reallocate the disclosed collateral interest into securities lending, then remove the exact corresponding amounts from the original categories. The filing says this would leave total net interest and its margin unchanged. Any forecast that simply adds the $362 million difference onto reported quarterly earnings would overstate income by the full amount of that reclassification.[1]

The model also needs to distinguish stock volume from monetisation. Average securities loaned rose by about three quarters, but the broader activity estimate rose by roughly one third. Their unequal growth rates show that notional activity and effective economic yield are not interchangeable. A rough ratio of activity interest to average securities loaned might illustrate a change in mix, but cannot be treated as a quoted lending rate: cash-collateral interest, other securities-borrowing activity and payment conventions all enter the numerator. The filing does not disclose enough matched components to identify how much of the gap is caused by rates rather than stock selection.[1]

What the figures establish

The narrow securities-borrowing-and-lending line fell 51%, while the company's broader activity estimate rose 36%. The difference reflects classification rather than missing revenue. The separate $37 million bridge to the income statement is essential when comparing this operating presentation with other brokers' GAAP results or with IBKR's own reported net revenue.[1]

The $427 million remains management's estimate, not a separately audited business-line profit or a pool distributable to retail clients. Future comparisons should retain three distinct measures: the named securities-lending row, the broader activity estimate and GAAP net interest income. Only after those definitions are aligned can changes in balances, interest rates and customer payments be interpreted reliably.[1]

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