Exponential Moving Average
An exponential moving average (EMA) is a moving average that gives more weight to recent prices and progressively less to older ones. As a result it reacts faster to new price moves than a simple moving average of the same length.
How the EMA works
Instead of averaging a fixed window equally, the EMA updates itself each period with a weighting factor. A common formula sets the factor at 2 divided by (N + 1), where N is the chosen length. For a 9-period EMA that is 0.2, meaning the newest close gets 20 percent weight and the previous EMA value gets 80 percent.
Because each new value builds on the last, older prices never fully disappear; their influence just fades exponentially over time. That is where the name comes from.
An example
Say a coin's 9-period EMA stands at 100 and the next candle closes at 110. The new EMA is 0.2 times 110 plus 0.8 times 100, which is 102. A 9-period SMA would only move by the difference between the new close and the one leaving the window, divided by 9, which is often less. In a fast move, the EMA catches up noticeably sooner.
Where EMAs are used
Short-term traders often prefer EMAs because they respond quickly. Common settings include the 9, 12, 21, 26 and 50-period EMAs. The widely used MACD indicator is built from the difference between a 12-period and a 26-period EMA.
As with other averages, traders look at the slope for trend direction, at price relative to the line, and at crossovers between a faster and a slower EMA.
Trade-offs and mistakes
Speed comes at a cost. Because the EMA reacts more to the latest prices, it is also more easily pulled around by short spikes and gives more false signals in choppy markets.
EMAs also need a starting value, often an SMA, so very early values can differ slightly between platforms. Most importantly, a faster average is still built on past data: it lags less, but it still lags, and it does not predict the next move.
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Frequently asked questions
Why use an EMA instead of an SMA?
Mainly for responsiveness. The EMA reflects recent price changes sooner, which some traders value for timing. The trade-off is more sensitivity to noise.
What are the most common EMA settings?
Frequently used lengths include 9, 12, 21, 26, 50 and 200 periods. The 12 and 26-period EMAs are notable because the MACD indicator is based on them.
Is the EMA more accurate than the SMA?
Not more accurate, just weighted differently. Each describes past prices; which one is more useful depends on the timeframe and how you use it.
Related terms
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