Interactive Brokers advertises 3.13% on client cash to pull RIAs off the incumbent custodians

Cash is the only part of the pitch carrying a published number, and it does arithmetic: about $313,000 a year on a $10m client cash book, with each percentage point of yield difference worth roughly $100,000 on the same balance ^[2]. That is real money to a firm running a few hundred million, and it is also money the payer can reset, which is the part of a yield-led sales motion that never appears in the deck.

The structural claim underneath it is more interesting than the rate. On Interactive Brokers' own telling, rivals monetise client cash through low-yield sweeps and negotiate pricing case by case ^[3], and most custodians also run their own advisory businesses ^[18]; a competitor who wants to match a published rate has to reprice an existing book to do it, which is a P&L decision rather than a marketing one. Stephen Caruso of Cerulli Associates, who calls Interactive Brokers an emerging custodian, puts it more bluntly: custody became an oligopoly in a lot of ways, and there is still a ton of room to grow in the RIA market ^[12].

What nobody outside can score is whether any of it moves assets. Amanda McLean, the firm's director of sales, institutional, declined to give Financial Planning specific metrics ^[4], and the only asset figure available is firmwide, more than $903bn across all affiliates ^[5], a pool that also holds direct retail, introducing brokers and prime ^[13]. So the equity case and the custody case are not the same case. Sandler analyst Chubak's view is that roughly 25% long-term account growth is sustainable and that the upfront cost of international expansion is already absorbed ^[13], and 25% compounding turns one account into about three in five years ^[1], which is what a 40% move in the stock this year is paying for ^[6]; RIA is one of three non-retail channels named in that thesis ^[13], not the thesis.

The counter-thesis, or rather the more interesting version of it, is Caruso's own: the inroads come from service and technology aimed at advisors rather than price, and his example is Altruist's Hazel planning agent, shipped the week after Altruist agreed to sell to Vanguard at a reported price above $4bn ^[17][10]. If that is right, published pricing buys Interactive Brokers a place on the multi-custodian list that advisors are already building ^[11] without buying the household, and the pitch, as described, buys nothing else: no platform acquisition, just service teams and a rate ^[19].

One artefact suggests the firm knows the fee argument alone is thin. Its website advertises RIA overperformance that beat the S&P 500's 2025 gain by 2.67 percentage points ^[9], which is a claim about client portfolio returns rather than about custody economics, and an odd thing for a custodian to put on the scoreboard.

The read the evidence supports is narrow: the pitch is cheap for Interactive Brokers to make and awkward for the incumbents to match, so it will keep being made, and its results remain invisible. An advisory-specific asset or account number would settle it in either direction.