# Exponential Moving Average (EMA)

Category: trend

EMA is a moving average that gives more weight to recent prices, making it more responsive to new information than a simple moving average.

## Formula

```text
EMA_today = (Price_today × K) + (EMA_yesterday × (1 - K))
where K = 2 / (N + 1), N = period length
```

## Common strategies

- EMA crossover: Fast EMA (9 or 21) crossing above slow EMA (50 or 200) is bullish; below is bearish.
- Dynamic support/resistance: Price bouncing off the 200 EMA in an uptrend.
- EMA ribbon: Multiple EMAs (8,13,21,34,55,89) stacked to visualize trend strength.

## How CommonQuant uses it

CommonQuant pre-calculates EMA(9), EMA(21), EMA(50), and EMA(200) on all timeframes. DSL strategies can reference ema(period) for any of these.

## Frequently asked questions

### EMA vs SMA — which is better?

EMA reacts faster to price changes, making it better for short-term trading. SMA is smoother and better for identifying long-term trends. See our /compare/ema-vs-sma page for a detailed comparison.

### What is the 200 EMA?

The 200-period EMA is widely watched as a bull/bear divider. Price above the 200 EMA is considered a bull market; below is a bear market.

Canonical: https://commonquant.ai/learn/indicators/ema