What are margin buying and short selling? Where the risks are

Margin buying borrows money from a broker to buy stocks; short selling borrows shares to sell. Both use leverage, so losses are magnified.

Updated：2026-11-15

The two terms

• Margin buying (financing): borrowing money from a broker to buy stocks, with the purchased shares as collateral, and repaying later. Used by those expecting prices to rise.
• Short selling: borrowing shares from a broker to sell first and buying them back later to return. Used by those expecting prices to fall.

Together they are margin trading, which needs a margin account and eligibility.

Why it is risky

• Leverage magnifies losses: trading with borrowed money (or shares) makes price moves count for more, and losses can exceed your own funds.
• Interest and fees: margin buying pays interest, short selling pays borrowing fees and deposits; costs rise the longer you hold.
• Maintenance ratio and margin calls: if collateral falls and the ratio drops below the required level (commonly about 130%; follow your broker’s rules), the broker asks for more funds; if you cannot, the collateral may be sold by force.
• Short selling specifics: when the price rises, a short seller’s loss has no upper limit, and the shares may be recalled early.

Margin balance and short-to-margin ratio

• Margin balance: the outstanding margin loans in the market, often used to gauge leverage.
• Short-to-margin ratio: short balance relative to margin balance.
• These describe current conditions and do not predict prices.

On this site

Market → Rankings has margin and short change rankings; the Chips tab of a stock page has its margin and short data; the home page and weekly report show the market’s margin balance changes.

This article only explains terms and risks. Tenmizu does not provide investment recommendations and this is not investment advice; margin trading rules follow the exchange and your broker.