Recently, many people have been asking whether stocks can be bought and sold on the same day. In fact, back in 2014, Taiwan's stock market already allowed day trading of spot stocks, and now the trading volume has accounted for nearly 40%, with more and more participants. Simply put, it's T+0 trading, also called day trading, meaning buying and selling within the same day to profit from the price difference in between.

Why do some people want to do day trading? Mainly because traditional stocks follow a T+2 settlement system, meaning you have to wait until the next day to sell after buying today. Many feel this causes them to miss opportunities. Day trading solves this problem by allowing immediate sell-offs, completing settlement on the same day, and avoiding overnight risk. My understanding is that, through broker-provided margin trading and securities lending functions, T+0 operations are achieved within the T+2 framework.

Spot stock day trading and margin securities trading are two main methods. Spot stock day trading involves using your own money to buy and sell within the same day, or selling first and then buying back. Margin trading involves borrowing money or stocks from the broker to operate. Both require meeting basic conditions such as having an account open for at least 3 months and executing more than 10 trades in the past year.

Regarding fees, for spot stock day trading, the securities transaction tax is 0.15%, and the commission fee is 0.1425%. Margin trading is slightly higher, with a securities transaction tax of 0.3%, commission fee of 0.1425%, plus an average borrowing interest rate of 0.08%. The total transaction cost per trade is about 0.29%. If you trade five times a day, the total cost rises to 1.45%, meaning stocks need to rise significantly to make a profit.

What are the benefits of day trading? The most obvious is that positions can be closed within the same day, allowing quick stop-losses without waiting until the next day. Theoretically, it's a no-capital business because a buy and sell are settled immediately, unlike normal trades that settle after two days. It also avoids overnight holding risks; if your judgment is wrong, you can sell immediately on the same day without being forced to hold until the next day.

But risks are not to be underestimated. Many are attracted to day trading because of the idea of "no capital needed," but this actually involves leverage, which increases risk. If you lack sufficient funds and still insist on day trading, a wrong direction could lead to huge debts. Additionally, short-term trading requires constant monitoring of the market, including individual stocks, the overall index, chips, news, and other factors—much more work than swing trading.

How many times can one day trade the same stock in a day? Taiwan's stock market doesn't have a clear limit; as long as you have enough funds or credit within trading hours, you can operate multiple times. But in practice, it's limited by capital constraints, stock type restrictions, etc. Not all stocks are available for day trading. Currently, only Taiwan 50, Mid-Cap 100, and about 200 stocks including the FTSE Taiwan Top 50 and OTC 50 can be day traded. Odd-lot trading is completely not allowed for day trading.

Besides spot stock day trading, futures, options, and Contracts for Difference (CFD) are inherently T+0 instruments, allowing same-day buying and selling naturally. Futures require tens of thousands of dollars in margin, options only need a few thousand yuan in premium, and CFDs have the lowest threshold, just a few tens to hundreds of dollars. Each tool has its characteristics: futures and options have expiration and settlement limits, while CFDs can be held indefinitely but carry significant leverage risks.

Ultimately, day trading is suitable for short-term investors who like to profit quickly from market volatility. But if your judgment or risk control is poor, losses can happen easily. The key is to understand your risk tolerance, not be fooled by the "no capital needed" myth, set stop-losses, and control leverage—these are the keys to long-term survival.