A wick, also called a shadow or tail, is a candlestick’s thin extension beyond its body. On a standard price candle, the upper wick reaches the period’s highest traded price and the lower wick reaches its lowest. The body connects the opening and closing prices, so a wick records prices reached outside that opening-to-closing span.
Measuring the excursion
If a candle opens at 100, closes at 104, reaches 110 and falls as low as 97, its upper wick spans 104 to 110 and its lower wick spans 97 to 100. The lengths are six and three price units respectively. A candle may have one wick, two or none when its extremes coincide with the body’s edges.
What a long wick suggests
A long upper wick shows that price traded higher before closing below that extreme. Traders sometimes describe this as rejection of higher prices. It does not identify who traded or prove a lasting reversal. The candle also cannot establish the order in which its high and low occurred. Interpretation depends on the interval, liquidity, surrounding price action and whether the candle has finished forming.