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Moving averages and crossover states
Updated 4 August 2026 · 3 min read · 14 Contents
Plain-language meaning
Moving averages smooth a selected price series. SMA weights the complete window equally; EMA updates recursively with greater recent weight; WMA uses a disclosed weight sequence. Crossovers compare two series or price with an average on completed bars.
Learning objectives #
You should be able to calculate an SMA, explain XMarketRadar's EMA seed, distinguish a continuing relationship from a fresh crossover, and state why differently seeded averages can disagree across platforms.
Core concept #
SMA(N) is the arithmetic mean of the last N valid values. XMarketRadar seeds EMA with the first N-value SMA, then updates using multiplier 2/(N+1); an interior unavailable value restarts the seed. A crossover is fresh only when the ordering changes between consecutive completed bars.
Method and conventions #
Record price input, periods, average type, seed and interval. Compare like with like. A 50/200 state remains positive on every bar where MA50 exceeds MA200, but the golden-cross event occurs only on the transition bar.
Use it in XMarketRadar #
Add one or more moving averages in charting, inspect legend parameters and warm-up, then use the scanner to distinguish state from fresh event where offered. Do not infer a crossover for rows whose prior bar or either average is unavailable.
Worked example #
For closes 96, 98, 100, 102 and 104, SMA(5)=100. If a fast average was 99 below a slow average of 100 yesterday and is 101 above a slow average of 100.5 today, today is a fresh upward crossover; later above-state bars are continuations.
How to interpret it #
A rising average describes the smoothed selected series. Shorter periods normally respond faster and contain more noise. Price above an average and a fast-above-slow state are related but different statements.
Limitations and common mistakes #
Common mistakes are comparing EMA values with different seeds, treating every above-state bar as a new cross, using insufficient warm-up, optimising periods on the evaluation sample and forgetting that a 20-period average changes clock duration with interval.
Market-specific differences #
Periods count venue sessions, not calendar days. A 200-session average spans different calendar lengths around holidays, and thinly traded listings can contain repeated closes that reduce responsiveness.
Key takeaway #
Key takeaway: average type, seed, period, input and fresh-versus-continuing state are part of the value—not optional implementation details.
Practice exercise #
Practice: compute SMA(3) over five values and mark the exact bar of a fast/slow crossover. Explain why the next bar is not another crossover if ordering remains unchanged.
Educational use only #
This chapter is descriptive education. It is not investment advice, a price prediction, a recommendation, a claim of predictive accuracy, or an instruction to buy, sell, rebalance or place an order.