Visual comparison of repainting versus non-repainting trading signals on a candlestick chart

Repainting indicator — what the history shows vs what actually happened
Repainting indicator comparison Shows how a repainting indicator displays a false buy signal in historical view that was not present in real time Historical view (what indicator shows now) Real-time view (what you actually saw) Apr 1 Apr 2 Apr 3 Apr 4 Apr 5 BUY Signal appears on Apr 3 in history Apr 1 Apr 2 Apr 3 Apr 4 now ? No signal existed in real time
Bullish candle
Bearish candle
Buy signal (historical — phantom)
Signal absent in real time
The indicator retroactively placed a buy signal on Apr 3 after seeing Apr 4 and Apr 5 data. In real time, no signal existed.
What happens to you: The historical backtest shows 94% accuracy. You trust it. You go live. The signals appear mid-candle and vanish when the candle closes. You enter on a phantom arrow and the market moves against you. The indicator was using future data to rewrite its own history.