Margin debt in Korean stocks: margin loans and forced selling

Why can borrowing to buy Korean stocks make a sell-off accelerate? Falling share prices can leave borrowers with insufficient collateral. Forced sales can then add pressure to a falling market, a risk identified by the Financial Services Commission (FSC).

Three forms of borrowing

The FSC distinguishes margin loans, stock-backed loans and purchases using partial deposits. A margin loan, or sinyong yungja, finances an individual’s share purchases. A stock-backed loan raises cash against shares already owned, without first selling them.

In a misu trade, an investor uses cash or eligible securities as an initial deposit and pays the remaining purchase amount in cash by settlement. That is T+2, the second settlement business day after the trade date; the Korea Exchange (KRX) excludes weekends and market holidays. The FSC’s educational guide describes forced selling at the T+3 opening if payment remains outstanding.

Using borrowed money to buy additional shares increases exposure relative to the investor’s own funds. A price decline can therefore produce a larger percentage loss on those funds. Interest adds a separate cost. The FSC cautions that loan terms vary by broker, security and customer classification.

For account-opening procedures and access to the local market, see our guide to how foreign investors can buy Korean stocks.

What triggers a forced sale

The collateral ratio expresses broker-recognised collateral value as a percentage of the outstanding loan. Falling collateral values can put an account below its required maintenance ratio. The broker then requests additional collateral using the customer’s agreed notification channel; missing that notice can mean missing the deadline for providing additional collateral, according to the Financial Supervisory Service (FSS).

Forced selling can follow if the shortfall is not resolved by the applicable deadline. Failure to repay at maturity is another liquidation trigger.

For collateral shares, forced-sale timing depends on the prior agreement between investor and broker. In 2016, the FSC removed the requirement to sell collateral shares in the opening auction following a borrower’s default, allowing the timing to be agreed in advance. The regulator said this would let brokers consider intraday prices and reduce excessive asset sales to recover debts. A timetable attached to one lending product cannot automatically be applied to another.

On November 6, 2026, the FSC announced a three-month exemption from securities firms’ 140% collateral-ratio maintenance obligation for margin loans, effective November 9. Investors should check their broker’s current notices and agreement for the requirements that apply to their account.

Why selling can feed on itself

Lower prices weaken collateral coverage. Unresolved shortfalls can trigger forced sales, which may push prices lower and weaken other borrowers’ collateral. The mechanism alone does not establish how much of a particular decline came from margin liquidation.

How to read a broker’s notice

The FSS guidance gives several practical checks:

• Confirm the agreed notification channel and the additional-collateral deadline.
• Check the final collateral ratio after the close; an intraday recovery can reverse.
• Read the forced-sale quantity formula. Brokers may calculate quantities using prices 15%–30% below a reference price, such as the previous close. The calculation price is not a guaranteed execution price.

The FSS says the calculation can result in the sale of all shares held in a security subject to forced selling. If disposal proceeds leave an unpaid balance, the broker can make further forced sales to recover it.