Fat-finger is a term used to describe human error when entering data or executing financial transactions, especially in the stock or crypto markets. These errors usually occur by accident, such as mistyping the wrong number or entering the wrong stock code, leading to incorrect transactions and sometimes having a major impact on market prices. A fat-finger error can occur when a trader or investor makes a mistake when entering the amount or price of the stock/crypto they wish to trade.

For example, a trader intends to buy 100 units of a stock but accidentally types 1,000 units, or wants to enter a selling price of $100 but mistakenly types $10. These errors can have a significant impact, especially if the wrong transaction is executed with a large volume.

It is not uncommon for this phenomenon to cause sudden and unexpected price volatility in the stock or crypto markets, especially when algorithmic trading systems are triggered by rapid price changes. In some cases, exchanges or financial authorities may cancel transactions caused by fat-finger errors if detected promptly. Apart from stock trading, fat-fingers can also occur in digital or crypto remittances, where an error in the wallet address or amount sent can lead to irrecoverable losses. Therefore, thoroughness and reconfirmation before executing a transaction is essential to avoid this type of error.