What is 반대매매 (a forced sale)?

It is the brokerage selling your shares without asking, to recover money you owe it. Two situations trigger it. If you bought on a credit loan (신용융자) and your collateral ratio falls below the maintenance level, the firm sells enough stock to restore the ratio. If you bought on margin you could not settle (미수금), the firm sells to cover the unpaid amount. In both cases the order is placed by the brokerage, not you, and you do not choose the price or the quantity.

When exactly does the forced sale happen?

For a credit-loan shortfall, you generally have until the next business day to deposit the additional collateral. If you do not, the sale is placed at the pre-open auction on the business day after that — commonly described as D+2 from the shortfall. Unpaid 미수금 runs off a different clock — it is measured from the settlement date, and the sale lands at the pre-open auction the business day after settlement, so the grace period is shorter rather than the calendar being shifted. Those are the standard timelines, not guarantees: firms reserve the right to liquidate immediately when the ratio falls far enough, with 120% a threshold some publish explicitly. Because the order goes in at the opening auction rather than during continuous trading, you cannot react to it once the market opens.

My shortfall is ₩1,000,000. Won't they just sell ₩1,000,000 of stock?

No, and this is the single biggest surprise in a margin call. The sale proceeds repay the loan at the discounted reference price, but the collateral falls by the full market value of the shares that left. So each share sold moves the numerator down faster than the denominator. Working through the algebra with a 140% ratio and a 15% discount, the shortfall is divided by only 19% of the share price — meaning about ₩5,270,000 of stock goes to cover a ₩1,000,000 shortfall. On a D or E grade stock at 20% off, the same shortfall takes about ₩8,340,000.

Do all Korean brokerages calculate this the same way?

The structure is the same everywhere; the parameters are not. Kiwoom, Mirae Asset and Shinhan all publish the same two tiers — 15% for high-grade stocks, 20% for low-grade — and Korea Investment's stated 85% reference price matches the 15% tier. Eugene Investment is the outlier: it sizes the sale from the daily lower limit with fees deducted, using a simpler formula. Maintenance ratios also vary, with Korea Investment publishing a 140% to 160% range that depends on the account and the stock. The letters on those tiers are not standardised either: Kiwoom labels the 20% tier D-E-Z, Mirae Asset D-E-F. This calculator adopts the shared 140% / 15% / 20% method and lets you override both numbers.

Where do I find my stock's grade?

Each brokerage assigns grades itself and lists them in its HTS or MTS credit-trading screens, usually under the margin or credit eligibility menu. They are not a market-wide standard, so the same stock can carry different grades at different firms. They are also revised on the firm's own schedule — a stock that is A grade this quarter can be D grade the next, which changes the discount from 15% to 20% and pushes the forced-sale quantity up by more than half. If you cannot find your grade, running the calculation at both 15% and 20% brackets the realistic range.

How do I avoid a forced sale?

Three levers, in order of cost. Deposit cash — it counts at face value and lifts the ratio immediately, and the shortfall figure here is exactly how much you need. Sell shares yourself before the deadline and use the proceeds to repay the loan. You sell at the market price rather than the discounted reference price, so the arithmetic is shortfall ÷ [price × (maintenance ratio − 1)] — at 140% that is 2.5 times the shortfall, against 5.3 times for the forced sale. Selling it yourself costs you roughly half the stock, and you pick the price. Or repay part of the loan, which lowers the denominator directly. The safe-price panel tells you how much cushion the position currently has; if the current price is only a few percent above that line, a single bad session can close the gap.

What is the difference between a 미수 and a 신용 forced sale?

미수금 is an unpaid settlement: you bought more than your deposit covered and did not fund the difference by settlement day. There is no ongoing loan and no maintenance ratio — the firm simply sells to recover the unpaid amount, and it moves fast, typically the pre-open auction on D+1. 신용융자 is a proper loan with a term, interest, and a maintenance ratio that is monitored continuously. It gives you a grace period and a chance to add collateral, but it is also the one where the sale can be many times the shortfall. This calculator models the credit-loan case.

The number here doesn't match what my brokerage says. Which is right?

Your brokerage. This is an estimate built from published formulas, and several real-world components are deliberately left out: accrued margin interest, brokerage commission, securities transaction tax, and any other unpaid amounts all get added to the shortfall before the quantity is worked out, which makes real sales larger than the figure here. Live prices are not fetched either, and the one price field stands in for two: the live price your ratio moves with, and the previous close the sale is actually sized from. Treat this as a way to understand the mechanism and see roughly how exposed a position is, then act on your brokerage's own notice.

Does this tool upload my data?

No. Everything runs right in your browser, so your data never leaves your device — it even works offline once the page has loaded.

⚠️ Margin Call Calculator (Korean Brokerages)

If your collateral ratio drops below the maintenance ratio your brokerage sets — 140% at most Korean firms — you have until the next business day to add cash. Miss that, and the firm sells your shares for you. The number that surprises people is not the shortfall but the sale: because the sale proceeds pay down the loan at a discounted price while your collateral drops at full market price, covering a ₩1,000,000 shortfall typically means selling ₩5,000,000 to ₩8,000,000 of stock. This calculator shows both figures, plus the share price at which the call would stop.

A margin call calculator for Korean credit-loan (신용융자) accounts: it takes your account totals — stock valuation, cash and loan — then returns your collateral ratio, the shortfall you must cover, and the number of shares a forced sale (반대매매) would liquidate.

Your account

The collateral ratio is worked out per account, not per stock. Every share in the account counts as collateral, plus cash, so read the total straight off your holdings screen.

Total value of every stock you hold (총 평가금액, KRW)

Cash (예수금, KRW)

Margin loan (신용융자금, KRW)

Maintenance ratio (담보유지비율, %)

Collateral ratio (담보비율)

—

Shortfall — cash to add (담보부족액)

—

Forced sale (반대매매 예상)

—

How far your stocks can fall

—

The stock they would sell

The ratio is an account-level number, but a forced sale happens stock by stock. Fill this in for whichever holding you expect to be liquidated.

Price — current or previous close (주가, KRW)

Shares held of that stock (그 종목 보유 수량)

Stock grade discount (종목등급 할인율)

Unpaid interest per share (1주당 융자이자, KRW)

Three ways out — and what each costs

Which method this uses

This uses the two-tier discount method Kiwoom, Mirae Asset, Shinhan and Korea Investment all publish: a forced-sale reference price of the previous close minus 15% for high-grade stocks and 20% for low-grade ones (this calculator treats the price you enter as that close), with the quantity sized to restore the collateral ratio rather than merely cover the gap — which is why the sale runs far larger than the shortfall. The details still vary between firms. The maintenance ratio defaults to 140%, the common baseline, but Korea Investment publishes a 140–160% band that depends on the account and the stock. Even the grade letters differ: Kiwoom labels the 20% tier D·E·Z, Mirae Asset D·E·F. And Eugene Investment does not use this formula at all — it sizes the sale off the daily lower limit (−30%) with fees deducted. Check your own brokerage's terms and edit the fields above to match.

Disclaimer

Estimate only. This is not investment advice, a solicitation, or a promise of what your brokerage will do.
Your brokerage's own terms and notices always take precedence. Maintenance ratios run 140–160% and vary by firm, by account and by stock.
Stock grades (A–Z) are reassigned by each firm on its own schedule. A stock that is A grade today can be D grade next month, which changes the discount and the share count.
Prices are what you type in; nothing is fetched live. Which price matters: brokerages size the forced sale off the previous close, while your collateral ratio moves with live prices. Type today's close after the market shuts and the sale figure matches what would go in at tomorrow's opening auction; type an intraday price and the sale figure runs high.
Unpaid margin interest is an input above, but brokerage commission, securities transaction tax and any other unpaid amounts are not modelled. Real forced sales fold those in before sizing the quantity, so the actual sale runs somewhat larger.
Timing is not modelled, and the two deadlines run off different clocks. For a credit-loan shortfall you have until the next business day to post collateral; miss it and the sale goes in at the pre-open auction the business day after that. Unpaid 미수금 is measured from the settlement date instead. Firms may also sell immediately if the ratio falls far enough (e.g. below 120%).
Enter the stock valuation your brokerage shows rather than a market total you worked out yourself. Shares posted as substitute collateral (대용증권) are not valued at full market price — they are marked to a 대용가격, the previous close times a per-stock rate that is often 70–80%.
Which holding gets sold is the brokerage's decision, not yours. Firms apply cash first, then collateral securities, then other securities, in an order set by their own terms. This calculator sizes the sale for one stock you nominate.
Nothing you enter leaves your browser — there is no upload and no server call. Your last inputs are kept in this browser's local storage so the form is still filled in when you come back; clearing site data removes them.

Private by design. This tool runs entirely in your browser — nothing you enter is uploaded or stored, and it works offline.

About

Korean credit-loan trading (신용융자) lets you buy shares with money borrowed from your brokerage. The shares you buy, plus everything else in the account, become the collateral for that loan. This is an account-level calculation, not a per-stock one: the published formula sums your credit-bought holdings, securities posted as collateral, substitute shares and cash, then divides by the total borrowed. Work out a ratio from one holding in isolation and it will read worse than the real one. Buy ₩20,000,000 of stock with a ₩15,000,000 loan and your ratio starts at 133% — already below the 140% most firms require, which is why leveraged positions can trigger a call on day one.

When the ratio falls short, two separate things happen and they use different arithmetic. The first is the shortfall: the cash you would have to deposit to bring the ratio back to the maintenance level, calculated as loan × maintenance ratio − collateral. The second is the forced sale, and its formula is the one that catches people out. Kiwoom, Mirae Asset, Shinhan and Korea Investment all size the sale so that the ratio is genuinely restored, not merely patched. Because shares are sold at a reference price marked down 15% (high-grade stocks) or 20% (low-grade), with the exact letters differing by firm, the loan falls by less than the collateral does. Solving for the point where the restored ratio holds gives shares = shortfall ÷ [price × (maintenance ratio × discount − 1)]. With a 140% ratio and a 15% discount, that denominator is only 19% of the share price — so the sale runs roughly 5.3 times the shortfall. At a 20% discount it is 8.3 times.

That multiplier is the whole reason this tool exists. A trader looking at a ₩1,000,000 shortfall reasonably expects to lose ₩1,000,000 of stock, then watches ₩5,270,000 leave the account at the opening auction.

Not every firm prices the sale the same way. Korea Investment states a reference price of 85% of the base price, which matches the 15% tier. Eugene Investment sizes its sale off the daily lower limit — roughly 30% below the close — with fees and transaction tax deducted, and uses a simpler formula rather than the ratio-restoring one, so its output differs from what this calculator produces. Maintenance ratios themselves are not uniform either: Korea Investment publishes a 140% to 160% band that varies by account and by stock, and some firms liquidate immediately rather than waiting when the ratio falls far enough, commonly below 120%.

The calculator therefore does two things deliberately. It adopts one representative method and names the firms it matches, so you know what you are looking at. And it exposes the maintenance ratio and the discount as editable fields, so you can enter your own brokerage's numbers instead of accepting a default that may not apply to you.

How to use

Start with the account, not a single stock. The collateral ratio is worked out per account: every share you hold counts as collateral, plus cash, against the whole loan. Read the total valuation straight off your holdings screen rather than multiplying one stock out by hand — enter one holding and the ratio comes out worse than it really is. Every field carries a "?" that opens a plain-language note if you are unsure what belongs in it. The calculator values every share you enter at full market price — which is right for stock bought on the loan, but not for shares you already owned and posted as extra collateral. Those are marked to a 대용가격 (previous close times a per-stock rate, often 70-80%), so including them makes the ratio look better than it is.
Enter the margin loan (신용융자금) and any cash in the account. The loan is the borrowed principal, not the total purchase amount; cash counts at face value and lifts the ratio directly, which is why a cash buffer is the cheapest protection against a call.
Now name the stock you expect to be liquidated, with its price and how many shares of it you hold. The ratio is an account-level number, but a forced sale runs stock by stock, so the quantity depends on that one holding. Which price to use also matters: brokerages size the sale off the previous close, so entering today’s close after the market shuts gives the figure that would go in at tomorrow’s opening auction.
Set the maintenance ratio. 140% is the default and the industry norm, but check your own brokerage — published bands run to 160%, and some accounts and stocks carry a higher requirement.
Pick the stock grade. High-grade stocks (A, B, C) use a 15% discount; low-grade ones use 20%. The letters on the low tier vary by firm — D-E-Z at Kiwoom, D-E-F at Mirae Asset. If your firm publishes a different figure, choose manual entry and type it in.
Read the three cards — current ratio, cash shortfall, forced sale — then the panel that prices the three ways out: deposit cash, sell it yourself and repay, or do nothing and let the brokerage sell. A separate panel shows the stock valuation at which a call begins, and how far above or below that line you sit right now. The panel below shows the share price at which the call stops, so you can see how much room the position has left.

FAQ

What is 반대매매 (a forced sale)?: It is the brokerage selling your shares without asking, to recover money you owe it. Two situations trigger it. If you bought on a credit loan (신용융자) and your collateral ratio falls below the maintenance level, the firm sells enough stock to restore the ratio. If you bought on margin you could not settle (미수금), the firm sells to cover the unpaid amount. In both cases the order is placed by the brokerage, not you, and you do not choose the price or the quantity.
When exactly does the forced sale happen?: For a credit-loan shortfall, you generally have until the next business day to deposit the additional collateral. If you do not, the sale is placed at the pre-open auction on the business day after that — commonly described as D+2 from the shortfall. Unpaid 미수금 runs off a different clock — it is measured from the settlement date, and the sale lands at the pre-open auction the business day after settlement, so the grace period is shorter rather than the calendar being shifted. Those are the standard timelines, not guarantees: firms reserve the right to liquidate immediately when the ratio falls far enough, with 120% a threshold some publish explicitly. Because the order goes in at the opening auction rather than during continuous trading, you cannot react to it once the market opens.
My shortfall is ₩1,000,000. Won't they just sell ₩1,000,000 of stock?: No, and this is the single biggest surprise in a margin call. The sale proceeds repay the loan at the discounted reference price, but the collateral falls by the full market value of the shares that left. So each share sold moves the numerator down faster than the denominator. Working through the algebra with a 140% ratio and a 15% discount, the shortfall is divided by only 19% of the share price — meaning about ₩5,270,000 of stock goes to cover a ₩1,000,000 shortfall. On a D or E grade stock at 20% off, the same shortfall takes about ₩8,340,000.
Do all Korean brokerages calculate this the same way?: The structure is the same everywhere; the parameters are not. Kiwoom, Mirae Asset and Shinhan all publish the same two tiers — 15% for high-grade stocks, 20% for low-grade — and Korea Investment's stated 85% reference price matches the 15% tier. Eugene Investment is the outlier: it sizes the sale from the daily lower limit with fees deducted, using a simpler formula. Maintenance ratios also vary, with Korea Investment publishing a 140% to 160% range that depends on the account and the stock. The letters on those tiers are not standardised either: Kiwoom labels the 20% tier D-E-Z, Mirae Asset D-E-F. This calculator adopts the shared 140% / 15% / 20% method and lets you override both numbers.
Where do I find my stock's grade?: Each brokerage assigns grades itself and lists them in its HTS or MTS credit-trading screens, usually under the margin or credit eligibility menu. They are not a market-wide standard, so the same stock can carry different grades at different firms. They are also revised on the firm's own schedule — a stock that is A grade this quarter can be D grade the next, which changes the discount from 15% to 20% and pushes the forced-sale quantity up by more than half. If you cannot find your grade, running the calculation at both 15% and 20% brackets the realistic range.
How do I avoid a forced sale?: Three levers, in order of cost. Deposit cash — it counts at face value and lifts the ratio immediately, and the shortfall figure here is exactly how much you need. Sell shares yourself before the deadline and use the proceeds to repay the loan. You sell at the market price rather than the discounted reference price, so the arithmetic is shortfall ÷ [price × (maintenance ratio − 1)] — at 140% that is 2.5 times the shortfall, against 5.3 times for the forced sale. Selling it yourself costs you roughly half the stock, and you pick the price. Or repay part of the loan, which lowers the denominator directly. The safe-price panel tells you how much cushion the position currently has; if the current price is only a few percent above that line, a single bad session can close the gap.
What is the difference between a 미수 and a 신용 forced sale?: 미수금 is an unpaid settlement: you bought more than your deposit covered and did not fund the difference by settlement day. There is no ongoing loan and no maintenance ratio — the firm simply sells to recover the unpaid amount, and it moves fast, typically the pre-open auction on D+1. 신용융자 is a proper loan with a term, interest, and a maintenance ratio that is monitored continuously. It gives you a grace period and a chance to add collateral, but it is also the one where the sale can be many times the shortfall. This calculator models the credit-loan case.
The number here doesn't match what my brokerage says. Which is right?: Your brokerage. This is an estimate built from published formulas, and several real-world components are deliberately left out: accrued margin interest, brokerage commission, securities transaction tax, and any other unpaid amounts all get added to the shortfall before the quantity is worked out, which makes real sales larger than the figure here. Live prices are not fetched either, and the one price field stands in for two: the live price your ratio moves with, and the previous close the sale is actually sized from. Treat this as a way to understand the mechanism and see roughly how exposed a position is, then act on your brokerage's own notice.
Does this tool upload my data?: No. Everything runs right in your browser, so your data never leaves your device — it even works offline once the page has loaded.