Margin Account: How It Works, What It Costs, and What the 2026 Rule Change Means

Opening a margin account does not mean borrowing money. It means signing an agreement that lets you borrow, lets your broker lend your shares to other market participants, and lets them sell your positions without asking first. Most people read only the first of those three. That gap between what a margin account is understood to be and what the agreement actually permits is where the expensive surprises live, and it has widened this year because the day-trading rules attached to these accounts changed in June 2026 while most published guidance still describes the old ones. Our stock trading guide covers where leverage belongs in a portfolio. This article walks the mechanics, the real carrying cost, the liquidation rules, the share-lending clause, and the current regulatory position.

What Is a Margin Account? The Short Answer

Having One and Using One Are Different Decisions

This is the distinction that matters most and it is almost never made. A margin account gives you a borrowing facility — a collateralized line of credit secured by the marginable securities you hold. It also gives you a set of capabilities that have nothing to do with borrowing: the ability to sell short, access to most options strategies, and the ability to reuse sale proceeds immediately rather than waiting for settlement.

Plenty of experienced traders open a margin account purely for that second list and never carry a loan balance. That is a reasonable position. Carrying debt is a separate decision with a separate cost, and conflating the two is why people either avoid margin accounts entirely when they should not, or borrow on them casually when they should not.

What It Takes to Open One

FINRA requires a minimum equity balance of $2,000 to open and maintain a margin account, and individual brokers routinely set higher thresholds of their own. You sign a margin agreement that governs the loan terms, the maintenance requirements, the broker’s liquidation rights, and the securities-lending clause covered later in this article. The agreement is binding whether or not you ever borrow a dollar.

How Buying Power Actually Works

Where the Second Ten Thousand Comes From

Deposit $10,000 into a margin account and Regulation T lets you buy roughly $20,000 of marginable securities. The initial requirement is 50%, so your $10,000 covers half the purchase and your broker lends the other half. That extra $10,000 is not a credit limit you can ignore — the moment you use it, a debit balance appears on your statement and interest starts accruing.

Buying power is therefore not the same thing as cash. Cash is yours. Buying power is a number that describes how much you could borrow, and every dollar of it you spend converts into debt secured by everything in the account, not just the position you bought with it.

Not Everything Is Marginable

Brokers set their own marginability rules on top of the regulatory minimums. Low-priced stocks, recent IPOs, thinly traded names, and highly volatile issues frequently carry requirements well above 50% or are excluded from margin entirely. Discovering that a stock is non-marginable after you have planned a position around 2:1 leverage is a common and avoidable frustration — check before you size.

Buying Power Moves With the Account

This is the part that catches people. Buying power is recalculated continuously off your account equity. Unrealized gains increase it and unrealized losses shrink it, which means your available leverage contracts at exactly the moment your positions are moving against you. The account tightens when you would most want flexibility, and that is not a malfunction — it is the design.

What Margin Actually Costs

Most explanations of margin mention interest in a single clause and move on. The carrying cost is the difference between margin being a tool and margin being a slow leak, so it deserves the arithmetic.

Daily Accrual, Monthly Posting, Tiered Rates

Margin interest is charged on your debit balance, accrues daily, and is typically posted to the account monthly — which means it compounds. Rates are tiered by balance size, and the tiers are steep: large borrowers pay materially less than small ones, and the headline rate a broker advertises for small balances is the highest one on the schedule.

The Break-Even Nobody Calculates

Here is the framing that changes decisions. A margin-funded position does not start making money when it goes up. It starts making money when it goes up by more than the interest rate. Borrow at 8% and the position must return more than 8% annualized before it has contributed anything at all.

The structural consequence is that margin is a short-horizon instrument. The interest cost is linear and certain — it accrues every single day regardless of what the market does. The return is neither linear nor certain. Time is unambiguously on the lender’s side, which is why margin suits a defined trade with a defined exit far better than an open-ended hold.

The Leverage Math: Why a 10% Drop Costs You 20%

Every article warns that leverage amplifies losses. Few show the mechanism, which is simpler and more brutal than the warning suggests: the loan balance is fixed while the position value moves. All of the movement lands on your equity.

Walking the Position Down

Start with $10,000 of your own money and $10,000 borrowed, buying $20,000 of stock. Here is what happens as the price falls.

A 10% decline in the stock produced a 20% loss of your capital. A 35% decline wiped out roughly 70% of it and pushed the equity percentage below the 25% FINRA maintenance floor, which is where the margin call arrives. Note that the loan never moved. That asymmetry is the entire mechanism, and no amount of conviction changes the arithmetic.

The Honest Other Half

Leverage is symmetric. The same 2:1 position turns a 10% gain into a 20% return on your capital, and that is precisely why margin exists and why experienced traders use it. The problem is not that leverage is dishonest about the upside — it is that the downside includes a forced-exit mechanism the upside has no equivalent of. If you want amplified exposure without a loan balance or a liquidation trigger, how leveraged ETFs work covers the alternative and its own decay trade-off.

Maintenance Margin and the Call

Maintenance margin is the minimum equity percentage you must keep in the account. FINRA sets a floor of 25%, and individual brokers routinely impose house requirements of 30% to 40%, higher still on volatile or concentrated positions. Those house requirements can be raised with little notice.

Who Decides What Gets Sold

Fall below maintenance and you receive a margin call: deposit funds or securities, or positions get liquidated. The part that surprises people is the control question. Your broker selects which holdings to sell. They are not obligated to consult you, they are not required to sell the position that caused the problem, and in fast-moving markets they can act without advance notice. Our explainer on what triggers a margin call walks the calculation, and margin account requirements covers the thresholds in detail.

One further point that is easy to miss: your liability is not capped at the account balance. If liquidation does not cover the loan, you owe the deficit. A margin account can, in principle, leave you owing your broker money after every position is gone.

Rehypothecation: What You Agreed To Without Reading

This clause is in every margin agreement, it is entirely legal and fully disclosed, and it appears in almost no retail-facing article about margin accounts. It deserves a section because it changes what you own in ways that surprise people.

Your Broker Can Lend Your Shares

Signing a margin agreement grants your broker the right to use securities in your margin account as collateral and to lend them to other market participants — typically short sellers, who need to borrow shares to sell them. Your shares can be on loan at any time and you are generally not notified when it happens.

What Changes When They Are Lent

Two practical consequences. Voting rights on shares that are out on loan generally do not come back to you for that meeting, because the borrower now holds the shares of record. And dividends arrive differently: instead of the company’s dividend, you receive a substitute payment from the borrower. Substitute payments are not qualified dividends, which means they are taxed as ordinary income rather than at the lower qualified rate.

That second point has a real dollar cost for anyone holding dividend payers in a margin account. A qualified dividend taxed at 15% becomes ordinary income taxed at your marginal rate, and nothing on your statement announces the change in advance.

How to Avoid It

Hold long-term dividend positions in a cash account, where no lending clause applies. If you want the margin account’s capabilities without the exposure, ask your broker how fully-paid securities are treated when the debit balance is zero — practices differ, and some brokers run separate opt-in lending programs that pay you for participation rather than taking it by default.

The 2026 Day-Trading Rule Change Nobody Has Updated

What the Old Rule Was

For over two decades, executing four or more day trades within five business days in a margin account flagged you as a pattern day trader. That designation carried a hard requirement: maintain at least $25,000 in account equity or lose the ability to day trade. It was the single most cited number in retail trading education, and it shaped how a generation of small accounts operated.

What Changed

FINRA eliminated that framework. Effective June 4, 2026, following SEC approval, the trade-counting mechanism is gone, the pattern day trader designation no longer exists, and the $25,000 minimum equity requirement attached to it has been removed. The standard $2,000 minimum equity requirement for margin accounts remains in place.

What replaced it is a risk-based intraday margin framework. Rather than counting trades and applying an end-of-day calculation, intraday buying power for margin customers is based on real-time intraday margin excess — the actual risk the positions represent during the session rather than the frequency with which they are opened and closed.

Why Your Broker May Still Enforce the Old Rule

Firms have an implementation window running to October 20, 2027. During that window a broker may operate under either framework. The practical consequence is that the correct answer to whether the $25,000 minimum applies to you is not a general one — it depends entirely on which broker holds your account and how far along their implementation is. Check the current policy on your broker’s own margin disclosure page before assuming either rule applies.

Margin Account vs. Cash Account: Which One You Need

The choice is less about risk appetite than about which capabilities you actually require. Here is the comparison that resolves it.

The Five Differences That Matter

The recommendation splits cleanly. Long-term buy-and-hold investors are generally better served by a cash account: no interest exposure, no securities lending, no forced liquidation, and the settlement constraint rarely binds when you trade a few times a year. Active traders usually need margin, because short selling and most options strategies are simply unavailable without it. Our comparison of cash account versus margin account covers the mechanics in more depth.

There is a sensible middle path that few people take deliberately: hold a margin account for the capabilities and run it at a zero debit balance. You get short selling and settlement flexibility, you pay no interest, and the only remaining exposure is the lending clause.

When Margin Makes Sense — and When It Destroys Accounts

The Defensible Uses

• Short-horizon positions with a defined stop, where the interest cost is bounded by a known holding period.
• Bridging a settlement gap for a few days rather than sitting out an opportunity waiting for funds to clear.
• Hedging an existing concentrated position you cannot sell without a tax consequence.
• Accessing short selling or options strategies while carrying no loan balance at all.

The Patterns That Destroy Accounts

Using margin to average down is the reliable killer. The position is already demonstrating that the thesis is wrong, and the response is to increase both exposure and debt against it. Every subsequent adverse move now works on a larger base with a fixed loan underneath. This single behavior accounts for more margin-related account destruction than any other.

Long-term holds on margin are the slower version of the same error. Interest accrues with certainty while returns do not, so time compounds against the borrower. And the sizing test is unforgiving: if a position would be too large for your account without leverage, leverage did not make it appropriate — it made it arrive faster. For the currency-market version of these dynamics, our guide to margin calls in forex trading covers a market where leverage ratios run far higher.

Where Leverage Belongs

In the core/satellite framework, the passive low-cost ETF core is never bought on margin — it is designed to compound through full cycles, and a forced-liquidation mechanism attached to a long-term compounding vehicle defeats its purpose entirely. Leverage belongs only in the rules-based active satellite, capped at a modest share of it. This article is educational and is not individualized investment advice.

The Bottom Line on Margin Accounts

A margin account and margin debt are two separate decisions, and the account’s terms bind you on both. The agreement governs share lending, liquidation rights, and your liability for any deficit whether or not you ever borrow a dollar — which is why the terms deserve more attention than the leverage math that gets all the coverage.

The framework:

• A margin account is a collateralized line of credit; using it and having it are different decisions.
• Regulation T gives roughly 2:1 initial buying power, and every dollar used becomes interest-bearing debt.
• Interest accrues daily and compounds monthly, so a position must out-earn the borrow rate to profit at all.
• The loan does not shrink with the position — a 10% price decline costs 20% of your equity.
• In a maintenance breach your broker chooses what to sell, without consulting you, and you owe any deficit.
• The margin agreement lets your broker lend your shares, converting dividends into ordinary-income substitute payments.
• FINRA eliminated the $25,000 pattern day trader minimum effective June 4, 2026, but brokers have until October 2027 to implement.
• Margin belongs in the active satellite with a defined exit, never in the passive core.

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Frequently Asked Questions

What is a margin account?

A margin account is a brokerage account that lets you borrow money from your broker to buy securities, using the assets in the account as collateral. Under Regulation T you can typically borrow up to 50% of a purchase, which roughly doubles your buying power and your risk. It also enables capabilities that do not require borrowing at all, including short selling, most options strategies, and immediate reuse of unsettled sale proceeds. FINRA requires a $2,000 minimum equity balance to open one, and individual brokers often set higher thresholds of their own.

How much money do you need to open a margin account?

FINRA requires a $2,000 minimum equity balance to open and maintain a margin account, and brokers can set higher requirements. The separate $25,000 minimum that applied to pattern day traders was eliminated by FINRA effective June 4, 2026, when trade-counting and the pattern day trader designation were replaced by a risk-based intraday margin framework. Firms have until October 20, 2027 to implement the change, so some brokers still enforce the old $25,000 threshold today. Confirm your own broker’s current policy rather than assuming either rule applies.

Is a margin account worth it?

It depends on which part you intend to use. The account itself unlocks short selling, most options strategies, and immediate access to unsettled proceeds, and many experienced traders maintain one for those capabilities while never carrying a loan balance. That is a defensible position with no interest cost. Carrying margin debt is the separate decision that requires justification, because interest accrues daily and with certainty while returns do not. For long-term buy-and-hold investors who need none of the capabilities, a cash account avoids the interest, the share-lending clause, and the forced-liquidation exposure entirely.

What happens if you can’t meet a margin call?

Your broker liquidates positions to restore the required equity level. Three things about that process surprise people. The broker chooses which holdings to sell, and it does not have to be the position that caused the shortfall. The broker is not obligated to consult you, and in fast-moving markets it can act without advance notice. And your liability is not capped at the account balance — if the liquidation proceeds do not cover the outstanding loan, you owe the remaining deficit. This is why maintaining a buffer above the house maintenance requirement matters more than knowing the number.