Recently, more and more people are looking into margin trading, but few retail investors truly understand what margin means. Let me share my observations.

Margin and short selling are essentially market sentiment thermometers. When you see the margin balance rising, it indicates that many people are borrowing money to buy stocks, usually during a bull market when confidence is sky-high. Conversely, a sharp decline in margin balance often means margin traders are selling stocks to pay back loans, sometimes taking profits, but more often being forced to liquidate or having their positions forcibly closed by brokers. Continuous large drops in margin balance are often accompanied by rapid stock price declines.

Short selling is also interesting. A high short interest balance indicates many are betting against the stock. But if the stock price doesn’t fall and instead rises, the short sellers get squeezed, forced to cover their positions, which can push the stock price even higher. Many experienced traders use these data points to judge whether the market is currently greedy or fearful.

Regarding the meaning of margin, simply put, it’s borrowing money from a broker to buy stocks. If you have 500k yuan and borrow another 500k yuan from the broker, you can buy 1 million yuan worth of stocks, which is called 2x leverage. The benefit is that gains are amplified during upward moves; if the stock rises 10%, your return on capital approaches 20%. During a bull market, this “accelerated feeling” can be quite addictive. But losses are also magnified—if the stock drops 10%, you lose 20%.

The real danger isn’t leverage itself, but being forced to sell during a decline. Many people don’t necessarily pick the wrong direction; they just get liquidated before a rebound happens.

I’ve seen an example. An investor bought a stock at 500 yuan using margin, putting in 200k yuan of their own money and borrowing 300k yuan from the broker. At that time, the margin maintenance ratio was 166.7%. Then, after a series of black swan events, the stock fell to 380 yuan, and the maintenance ratio dropped to 126.7%. The broker started to get nervous. If the stock keeps falling, the investor’s 300k yuan could be wiped out, so the broker notified the investor to add collateral. If they don’t do so within two days, the broker has the right to sell the stock directly. That’s a forced liquidation.

There are two ways to meet the margin call: one is to top up to maintain a ratio above 130%, which temporarily prevents the broker from selling the stock. But if the stock continues to fall and the ratio drops below 130%, the broker will notify you to add funds again, or they will liquidate the position the next day. The second is to restore the ratio to above 166.7%, returning to the initial level. That’s why during big market swings, news often reports “margin calls,” “stocks facing mass forced liquidations,” etc.

And then there’s interest. Borrowing to buy stocks incurs interest, usually between 6% and 10%. If the stock price remains stagnant for a long time, holding the stock might break even or slightly profit, but the interest costs will eat into gains. Borrowing 1 million yuan for a year at 6-10% means paying 60,000 to 100k yuan in interest. So margin trading is more suitable for swing trading, not for buy-and-hold investors.

Short selling involves borrowing stocks from the broker to sell, hoping to buy them back at a lower price later to profit from the difference. But shorting is more difficult than going long because stocks tend to fall quickly but rebound more violently. Hot stocks often experience “short squeezes,” where short sellers are forced to cover, pushing the price even higher. The 2021 GME incident is a classic example, where many short funds were squeezed out by retail investors.

Short selling also carries risks. First, there’s a time limit—before dividends or shareholder meetings, you must cover your short position. Second, if the stock doesn’t fall and instead rises, your losses can grow, and you face the risk of a margin call and forced liquidation. Third, there’s the risk of being “squeezed” out—since short positions have expiration dates, brokers will force you to cover. Some investors specifically target stocks with high short interest to push the price up, then cover their short positions for profit once the price rises.

I’ve seen some common mistakes among retail investors. First, treating margin as an ATM. During a bull market, making several consecutive profits can lead to the belief that “this is easy money.” But markets don’t go up forever; a reversal can wipe out multiple profits in one go. Second, averaging down as the stock falls. This is the most dangerous move—if the stock drops 10%, your loss is magnified, and adding more margin accelerates the decline, often leading to forced liquidation. Third, turning a short-term trade into a long-term hold. If you initially only plan to hold for a month but get stuck, you might think “holding for dividends isn’t bad.” But margin incurs interest, and as the stock price drops, your margin ratio decreases, making “holding” impossible. Fourth, ignoring interest costs, which can be substantial over the long term.

If you want to use margin, I recommend a few strategies. First, choose stocks with larger market caps and good liquidity. Avoid small companies with extreme volatility, as you might get liquidated before the stock rises. Also, avoid stocks with very low volatility and dividend yields of only 4-5%, as the interest costs can outweigh the gains.

Second, always set stop-loss and take-profit points. Margin amplifies gains and losses, so discipline in cutting losses and locking in profits is crucial. Use technical analysis—stop-loss when breaking support levels, take profit at resistance zones. Disciplined investing is the key to long-term success.

Third, buy in stages to lower average cost or diversify across industries. Since we can’t predict the future or pinpoint the exact bottom, using fundamental and technical analysis can help identify relatively low points for staggered entry. If your first purchase is near the bottom, you can participate in subsequent gains. If the stock continues to fall but you remain confident, you can add second and third tranches. Also, spreading your capital across multiple stocks can increase your chances of success, especially with margin, allowing you to diversify investments and improve overall expected returns.

Ultimately, investing is about understanding the underlying assets and the overall economy, combining technical analysis to judge price movements, and using appropriate tools to profit from the market. Margin trading and short selling are neither inherently “good” nor “bad” tools. When the market is good, leverage can seem like a shortcut to amplified gains; but when the trend reverses, it can also magnify emotional panic. Understanding what margin means, grasping market dynamics, and using tools wisely are the keys to consistent investing success.