Exchange Act Rule 15c3-3: Reserves, Custody, and Daily Requirement

Exchange Act Rule 15c3-3, the SEC’s Customer Protection Rule, requires every broker-dealer that holds customer cash or securities to keep those assets strictly separated from the firm’s own money and positions. The rule does two things at once. It forces the firm to physically safeguard customer securities in designated locations where no one else has a claim on them, and it forces the firm to set aside enough cash in a protected bank account to cover, at all times, the net amount it owes its customers. If the firm fails, those assets are supposed to be sitting there ready to be returned.¹

The rule sits alongside the Net Capital Rule (Rule 15c3-1) as the backbone of broker-dealer financial responsibility. Net capital keeps the firm solvent enough to wind down; the Customer Protection Rule keeps customer property out of that wind-down entirely.

Who Counts as a Customer

Rule 15c3-3 defines a customer as any person from whom, or on whose behalf, the broker-dealer has received, acquired, or holds funds or securities. Most retail investors and institutional clients meet this test the moment they deposit assets for trading or safekeeping.²

Several groups are explicitly outside the definition. General partners, directors, and principal officers of the firm are not customers. Anyone whose claim is part of the firm’s capital, or is subordinated to the firm’s creditors, is also excluded. Other broker-dealers acting for their own account, municipal securities dealers, and government securities dealers fall into a separate “non-customer” or PAB category with its own reserve treatment.³

Possession or Control of Customer Securities

Rule 15c3-3(b) requires broker-dealers to obtain and maintain physical possession or control of every “fully paid” and “excess margin” security a customer owns. Fully paid securities are shares or bonds the customer has paid for in full without borrowing from the firm. Excess margin securities are the portion of a margin customer’s holdings whose value exceeds 140 percent of what the customer owes. The firm cannot pledge, lend, or otherwise encumber those specific securities for its own account.³

The rule spells out where those securities are allowed to sit. Approved “good control locations” include clearing corporations and depositories such as the Depository Trust Company, banks that have acknowledged in writing that they hold no lien on the securities, omnibus accounts at another broker-dealer where the carrying firm has been told to hold the securities free of liens, foreign depositories and custodians specifically designated by the SEC, and securities in transit between the firm’s own offices or out for transfer within tight time limits. The common thread is that the firm can retrieve the securities without paying anyone and no third party has a claim.³

Firms run a daily check for “shortages,” meaning securities that ought to be under the firm’s control but currently aren’t. When loaned securities are recalled and don’t come back within five business days of notice, the firm has to buy in equivalent securities on the open market. Securities stuck in a fail-to-receive status past 30 calendar days trigger buy-in procedures no later than the next business day.²

The Special Reserve Bank Account

Rule 15c3-3(e) requires every carrying broker-dealer to maintain a Special Reserve Bank Account for the Exclusive Benefit of Customers. This account holds the net cash the firm owes its customers, walled off from the firm’s own bank accounts. The firm cannot use these funds for operations, proprietary trading, or any other corporate purpose.³

Money in the account can only be invested in “qualified securities,” defined as securities issued or guaranteed as to principal and interest by the United States government. No corporate paper, no money-market instruments beyond Treasuries. The firm must obtain a written agreement from the bank stating that the funds will not be used to satisfy any debts the broker-dealer owes to the bank. If the firm files for bankruptcy, assets in this account are legally shielded from the claims of the firm’s general creditors.³

How the Reserve Amount Is Calculated

Exhibit A to Rule 15c3-3 sets out the formula. The calculation weighs credits (what the firm owes customers) against debits (what customers owe the firm).⁴

Credits include free cash sitting in customer accounts, money the firm has borrowed using customer securities as collateral, proceeds from lending out customer securities, and the value of customer securities the firm has failed to receive from counterparties. Debits include margin loans customers owe the firm, securities borrowed to cover customer short sales, customer fails-to-deliver less than 30 days old, and margin deposited at the Options Clearing Corporation for customer option positions. Doubtful or unsecured balances don’t count as debits; only realistically collectible amounts offset the credit side.⁴

When credits exceed debits, the difference is the minimum the firm must have on deposit. The deposit must land no later than one hour after banking business opens on the second business day following the computation.²

Weekly, Monthly, and the 2026 Daily Requirement

Most firms compute the reserve formula weekly, as of the close of the last business day of the week. Firms permitted to compute monthly must deposit at least 105 percent of the net credit balance to compensate for the less frequent snapshot.⁴

In 2024, the SEC adopted amendments requiring broker-dealers with average total credits of $500 million or more to compute the reserve daily rather than weekly. The compliance date, originally December 31, 2025, was extended to June 30, 2026, to give firms more time to build and test the systems.⁵ Firms that voluntarily adopt daily computation can reduce the aggregate debit items haircut from 3 percent to 2 percent, which modestly lowers the required deposit. To qualify, the firm must notify its designated examining authority in writing at least 30 calendar days before switching.⁶

A Separate Reserve for Other Broker-Dealers

Broker-dealers that carry accounts for other broker-dealers must maintain a second reserve account, the Special Reserve Bank Account for Brokers and Dealers, commonly called the PAB Reserve Bank Account. It uses the same basic Exhibit A formula, treating references to “customer” as references to PAB accounts, but with several tightenings. Credits already counted in the customer reserve cannot be double-counted. Certain reductions available in the customer formula, such as the 1 percent debit balance reduction under Note E(3) and the aggregate debit items haircut under Note E(1), don’t apply. The PAB math is stricter, reflecting the different risk profile of inter-dealer obligations.⁷

Exemptions Under Section (k)

Not every registered broker-dealer is subject to the full rule. Section (k) exempts firms whose business models don’t create the risks the rule targets, but the exemptions are narrow and easy to lose.

The (k)(1) exemption covers firms whose principal and brokerage transactions are limited to mutual fund shares and insurance company separate accounts, and that promptly transmit all funds and securities without ever holding customer property. The (k)(2)(i) exemption applies to firms that carry no margin accounts, promptly transmit all customer funds and securities, and route all financial transactions through designated bank accounts labeled “Special Account for the Exclusive Benefit of Customers.” The (k)(2)(ii) exemption covers introducing brokers that clear all customer transactions on a fully disclosed basis through a clearing firm, so they never handle customer assets directly.³

The SEC and FINRA have warned that firms sometimes claim a (k) exemption they don’t actually qualify for. If a firm holds customer cash even briefly, or misses a prompt-transmittal deadline, it can fall outside its claimed exemption and become subject to the full rule without recognizing the shift. A minor operational slip can turn into a major compliance violation.

What Happens When a Firm Falls Short

When a broker-dealer fails to make a required deposit into either reserve account, Rule 15c3-3(i) requires immediate notification to the SEC and the firm’s designated examining authority, typically FINRA. The rule specifies notification by telegram; FINRA interpretations recognize other prompt methods such as registered letter, followed by written confirmation. The notice must state the amount of the deficiency and explain why the deposit wasn’t made on time.²

Even a hindsight deficiency counts. If the firm later discovers that an error in a past computation caused an undetected shortfall, notification is still required, even where the firm is currently in compliance. The notice should describe the error and the steps taken to prevent recurrence.²

The SEC treats reserve deficiencies as serious violations. Regulators can restrict a firm’s ability to take on new business until the reserve is fully funded, along with imposing censures and fines. In one enforcement action, the SEC charged Wedbush Securities with failing to properly safeguard customer cash and securities under Rule 15c3-3; Wedbush consented to disgorgement and prejudgment interest of $304,197 plus a $1 million civil penalty without admitting or denying the findings.⁸

How the Rule Fits With SIPC Protection

Rule 15c3-3 is preventive; SIPC is a backstop. The rule keeps customer assets segregated so they are available for return if a firm fails. When a broker-dealer is liquidated and the segregated assets still fall short, SIPC steps in up to statutory limits: $500,000 per customer in total, with a $250,000 sublimit for cash claims.¹

When the rule works, SIPC rarely has to advance significant funds, because the customer property is already sitting in segregated accounts and control locations waiting to be returned. The largest SIPC payouts have historically come from firms that violated Rule 15c3-3, not firms that followed it.

1
U.S. Securities and Exchange Commission. Statement on Customer Protection Rule
2
FINRA. SEA Rule 15c3-3 and Related Interpretations
3
eCFR. 17 CFR 240.15c3-3 – Customer Protection, Reserves and Custody of Securities
4
eCFR. 17 CFR 240.15c3-3a – Formula for Determination of Customer and PAB Account Reserve Requirements
5
U.S. Securities and Exchange Commission. Daily Computation of Customer and Broker-Dealer Reserve Requirements
6
U.S. Securities and Exchange Commission. SEC Adopts Rule Amendments to the Broker-Dealer Customer Protection Rule
7
FINRA. SEA Rule 15c3-3
8
U.S. Securities and Exchange Commission. Wedbush Securities Settles SEC Charges That It Failed to Comply With Customer Protection Rule