Margin Calls and Maintenance Requirements: A Retail Investor Guide

Margin calls start with a number, not a warning

A margin account is a loan secured by the securities you hold. That framing explains almost everything about margin calls for retail investors: the broker is not asking for your opinion, it is checking whether the collateral still covers the loan. Two separate tests decide that — an initial requirement when you open a position, and a maintenance requirement you have to satisfy every day the position stays open.

Most retail investors focus on the first and get surprised by the second.

Initial margin: the entry ticket

For US broker-dealers, Regulation T sets the standard. Under the supplement at Section 220.12 of Regulation T, a long position in a margin equity security requires 50% of the current market value in equity, and a short sale of a non-exempted security requires 150% of current market value. That 50% figure is not a recent tightening; it has governed the standard initial requirement for decades.

Maintenance margin: the test you live with

FINRA Rule 4210 sets the ongoing floor. Paragraph (c) puts the minimum maintenance requirement at 25% of current market value for long margin securities. For short equity positions it is the greater of $5.00 per share or 30% of market value for stocks at $5.00 or above, and the greater of $2.50 per share or 100% of market value below that threshold. Non-margin-eligible securities held long get no loan value at all — 100% of market value.

House requirements are the ones that bite

Rule 4210(d)(1) requires every firm to establish procedures to "review the need for instituting higher margin requirements, mark-to-markets and collateral deposits than are required by this Rule for individual securities or customer accounts." The rulebook is a floor, not your number. A broker that applies 35% or 40% maintenance to a volatile or concentrated position will issue calls earlier and liquidate sooner than the FINRA minimum suggests. The document that defines your call price is the maintenance schedule attached to your account type, and the margin disclosure statement you received at opening — not the rule text.

The baseline requirements at a glance

The first four rows come from FINRA Rule 4210(c). The leveraged rows reflect FINRA Regulatory Notice 09-53, which raised the margin requirement for leveraged exchange-traded funds and their associated uncovered options by a factor commensurate with the leverage. In practice, the 25% long requirement scales with the multiplier — 1.5x to 37.5%, 2x to 50%, 3x to 75% — and the 30% short requirement scales to 90% at 3x. Long requirements are capped at 100% of position value; short requirements are not.

Margin call math: two worked examples

The numbers below are illustrative arithmetic, not market data. The trigger is simple: a call occurs when account equity falls below the maintenance percentage multiplied by position value. Equity equals position value minus the loan, so the size of the decline that triggers a call depends only on how much you borrowed.

Example 1: $20,000 of stock bought with $10,000 down

You buy 500 shares at $40, paying $10,000 equity and borrowing $10,000. Position value is $20,000.

At the 25% FINRA floor, a call arrives when equity falls to 25% of value — a position value of about $13,333, or roughly $26.67 per share, a 33% decline from $40.

At a 40% house requirement, the call arrives at a position value of about $16,667 — roughly $33.33 per share, a 17% decline. Same trade, half the cushion.

Equity percentage, not account size, is the metric. A smaller account does not get more room; it gets the same squeeze with less cash to fix it.

Example 2: a 3x leveraged ETF

You buy $30,000 of a 3x index ETF, expecting to post the standard 50% deposit of $15,000. Because the maintenance requirement for a 3x product is 75%, that trade is under-margined at settlement: the position needs $22,500 of equity, leaving a $7,500 loan.

That buffer looks comfortable until the daily reset works. A 10% down day for the index means the fund falls roughly 30%, to $21,000. Equity is then $13,500 against a $15,750 requirement — a $2,250 deficiency, and a call, after one trading day. The fund now needs roughly a 42.9% gain to return to $30,000, because the index itself needs about 11.1% to get back to where it started. That gap is the daily reset at work.

What happens when the call arrives

A maintenance call is a demand, not a negotiation: deposit cash or marginable securities, or reduce the position, by the deadline in your margin agreement — commonly the next trading session, sometimes sooner for intraday deficiencies. FINRA's margin account guidance is direct about the consequence: the firm can sell securities without contacting you, and it chooses which positions to liquidate. If the proceeds are not enough, the account can go into deficit and you still owe the balance.

Two practical points follow. A broker has no obligation to warn you before a call, and margin agreements typically allow it to sell first and notify afterwards. And with T+1 settlement now standard in the US — the SEC's 2023 adopting release shortened the standard cycle from T+2 to T+1, with a compliance date of 28 May 2024, as announced by the Commission — sale proceeds arrive quickly but not instantly. Unsent cash is not collateral until it is in the account.

The day trading margin rule has been replaced

Accounts that made four or more day trades in five business days, where those trades exceeded 6% of total trades, were once treated as pattern day traders subject to a $25,000 minimum equity requirement under Rule 4210(f)(8)(B). FINRA has removed that framework. In Regulatory Notice 26-10, FINRA set out new intraday margin standards — effective 4 June 2026, with a phase-in period ending 20 October 2027 — approved by the SEC in its order on the rule change. Under the new paragraph (d)(2), firms must determine an "intraday margin deficit" for each margin account on any day a transaction reduces the account's intraday margin level. The practical effect is that intraday exposure, rather than a day-trade count, drives the requirement. Because the industry is inside the phase-in window, it is worth confirming with your broker which standard applies to your account today.

What meeting a call actually costs

There are only three ways to answer a maintenance call, and each has a price.

Adding cash. Cheapest in tax terms — no realisation, no spread — but it concentrates more of your net worth in a position that just moved against you.

Selling other holdings. This realises gains and losses, creates bid-ask and market-impact costs, and usually happens under time pressure — the worst moment to choose an order type. Our notes on order types explain why that matters.

Borrowing more. Not an answer at all. Margin interest accrues daily on the debit balance and posts monthly, and the rate comes from your broker's published schedule, not from a market-wide figure. Schwab's current standard margin rates, with a base rate of 10.25% last changed on 18 September 2026, show an effective rate of 12.075% on debit balances under $25,000, falling to 10.325% at the $250,000–$500,000 tier. On that under-$25,000 rate, a $10,000 debit carried for 90 days costs roughly $298 in interest — on top of the loss that caused the call. Other brokers publish different schedules and change them without notice, so read your own broker's current one.

Portfolio margin accounts, which require a minimum of $100,000 in equity under Rule 4210(g) and use risk-based calculations, produce different numbers — different arithmetic, not less risk.

Leveraged ETFs: margin multiplied by daily reset

Leveraged ETFs are margin-eligible, but they carry two independent costs. The first is the leverage-scaled maintenance requirement above: a 3x product needs 75% equity, under the approach set out in Regulatory Notice 09-53. The second is the daily reset. Geared funds are designed to deliver a multiple of the underlying index's return for a single day, not over longer periods, and their offering documents say so explicitly.

The arithmetic is unforgiving. A 10% fall followed by a 10% rise leaves an unleveraged index down about 1%, while a 3x fund is down about 9% — two days is enough to open a visible gap. Add the fund's expense ratio, which for geared products runs higher than for a plain index fund, and the financing costs the manager pays to build the leverage, which do not appear in the headline fee. Because both change over time, check the fund's current prospectus rather than an old expense figure.

Risks and costs

The list is short but not gentle.

• Forced liquidation at the worst moment. Brokers sell into the decline that caused the call, converting an unrealised loss into a permanent one, and they choose which holdings to sell.
• Gap risk. Overnight and weekend gaps can take an account from comfortable to deficient before you can react.
• Margin interest compounds. It accrues daily on the debit balance and is charged whether the position is winning or losing; rates differ sharply by broker and by balance tier.
• Leveraged product decay. Daily resets hurt most in choppy, high-volatility markets, and the drag scales with the square of volatility.
• Short positions. Losses are not capped by a floor price, and the maintenance requirement is higher than for long positions.
• Rule and jurisdiction differences. The thresholds described here are US broker-dealer requirements under Regulation T and FINRA Rule 4210. In the EU and the UK, the margin you post and the close-out rules that apply are set by your broker under national and local supervisory frameworks, and the leveraged products available to retail clients differ. Tax treatment of margin interest and of forced sales is jurisdiction-specific.
• Concentration. A single large position in a margin account turns one bad earnings report into a portfolio-level event. Our framework for sizing so that a single trade cannot do that is in Position Sizing and Risk per Trade.

Bottom line

Initial margin determines whether you can open a trade; maintenance margin determines whether you keep it. The arithmetic shows why the cushion matters more than the entry requirement: a house requirement of 40% halves the decline that triggers a call compared with the 25% floor, and a 3x ETF needs 75% equity before it is properly margined at all. Margin interest is a real, ongoing cost priced off your broker's schedule, and leveraged ETFs add a second cost through the daily reset. Because the day trading framework is inside a phase-in period that runs to October 2027, the current requirements are worth confirming with your broker rather than assuming last year's numbers still apply.