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Moving Average

OVERVIEW

A moving average (MA) is a statistical line plotted on a price chart that averages the last N bars' closes — or another chosen input — and re-computes every bar. As the window slides forward in time, the oldest bar drops off and the newest bar enters, producing a smooth curve that follows, but lags, the raw price.

Note

A moving average answers one question precisely: over the last N sessions, is the prevailing price above or below where it has been on average?

Moving averages are the single most-used indicator in technical analysis and form the foundation of trend-following, regime filtering, and crossover systems.

CALCULATION METHODS

Tapeboard supports four moving average types. Select the type from the indicator settings panel on any chart.

Type Formula Weight Distribution Best For
SMA (P₁ + P₂ + … + Pₙ) / N Equal across all bars Trend definition, 50/200-day analysis
EMA α × Pₜ + (1 − α) × EMAₜ₋₁ where α = 2 / (N + 1) Exponentially heavier on recent bars Earlier turn detection, shorter-term trading
WMA Linearly decaying weights Heavier on recent bars, lighter on oldest Moderate lag reduction
VWMA Each close weighted by bar share volume Volume-proportional Volume-confirmed trend reading
HMA Reduced-lag construction Near-zero lag Short-term traders requiring fast response

Tip

A 20-period EMA uses α ≈ 0.0952. Today's close contributes 9.5% of the new value; the remaining 90.5% carries forward from yesterday's EMA. Switch to EMA when you need roughly twice the price sensitivity of an equivalent-period SMA.

WORKED EXAMPLE

Metric Value
Date 2026-04-17
Instrument SPY
Closing price $547.12
50-day SMA $535.00
Price vs. 50-day SMA +2.26%
200-day SMA $518.40
Price vs. 200-day SMA +5.5%
50-day vs. 200-day SMA +3.2%

Both the 50-day and 200-day filters align long — a measurable bullish tilt across timeframes.

SMA vs. EMA sensitivity on the same series: A single gap-up day of +1.5% shifts the 20-SMA by 0.075% but the 20-EMA by 0.143% — roughly twice as sensitive. This is the trade-off traders accept when prioritising earlier turns over reduced whipsaws.

HOW TO USE

Trend Definition

Place a 200-day MA on any daily chart. Price sustained above a rising 200-day MA indicates a structural uptrend (Weinstein and Minervini frameworks). Use the 50-day crossing above the 200-day — a golden cross — as a secondary confirmation signal.

Dynamic Support and Resistance

Crowd-watched periods (20, 50, 200-day) become self-fulfilling pivots. Dip-buyers cluster at these levels, increasing the probability of a reaction — but not guaranteeing one.

Note

A 200-day MA touch is a probability tilt, not a hard bounce line. Treating it as guaranteed support confuses a descriptive statistic with a structural level.

Crossover Systems

  • Price/MA crossover — price closing above or below the MA triggers a directional signal.
  • Fast/slow MA crossover — a shorter-period MA crossing a longer-period MA (e.g. 50/200) forms the backbone of systematic trend-following strategies.

Regime Filtering

Mechanical strategies commonly require the benchmark index (e.g. SPY) to trade above its 200-day MA before accepting any long signal. This filter substantially cuts drawdown during bear markets.

LIMITATIONS

Limitation Detail
Lag A 50-day SMA lags price by approximately N/2 bars (~25 sessions). In a sharp reversal, the MA confirms the new trend only after much of the move has passed.
Whipsaw in ranges In choppy or sideways markets, MA crossover systems repeatedly buy highs and sell lows as breakouts fail to follow through.
Period selection The "right" period (50, 89, 200?) is typically curve-fit to a backtest window and degrades out of sample.
Input blindness An MA is a function of closes only — it ignores intrabar volatility, volume, and gaps.

Tip

Combine moving averages with a complementary indicator such as RSI or MACD to reduce false signals in low-trend environments.