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Introduction

Stock charts support comparing multiple securities by overlaying their price movements on the same chart. Comparisons automatically switch to percent scale mode to normalize different price ranges.

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Adding Comparison Series

Add a comparison series using addComparingSeries(): 
import * as am5xy from "@amcharts/amcharts5/xy";

// Create comparison series
const comparingSeries = am5xy.LineSeries.new(root, {
  name: "AAPL",
  valueYField: "Close",
  valueXField: "Date",
  xAxis: dateAxis,
  yAxis: valueAxis,
  calculateAggregates: true,
  legendValueText: "{valueY.formatNumber('#.00')}"
});

// Add to stock chart
const compSeries = stockChart.addComparingSeries(comparingSeries);

// Load data
compSeries.data.setAll(appleData);
Comparison series are typically line series for clearer visual distinction from the main candlestick series.

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Percent Scale Mode

When comparison series are added, the chart automatically switches to percent scale mode: 
const stockChart = root.container.children.push(
  am5stock.StockChart.new(root, {
    autoSetPercentScale: true // Default
  })
);
Percent scale normalizes all series to show percentage change from a common starting point.

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Manual Percent Scale

Manually control percent scale mode: 
// Enable percent scale
stockChart.setPercentScale(true);

// Disable percent scale
stockChart.setPercentScale(false);

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Percent Scale Settings

Customize how the main series appears in percent scale mode: 
const stockChart = root.container.children.push(
  am5stock.StockChart.new(root, {
    percentScaleSeriesSettings: {
      valueYShow: "valueYChangeSelectionPercent",
      openValueYShow: "openValueYChangeSelectionPercent",
      highValueYShow: "highValueYChangeSelectionPercent",
      lowValueYShow: "lowValueYChangeSelectionPercent"
    },
    percentScaleValueAxisSettings: {
      numberFormat: "#.00'%'",
      extraMin: 0.1,
      extraMax: 0.1
    }
  })
);

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Comparison Control

Add a comparison control to the toolbar for user-friendly comparisons: 
const comparisonControl = am5stock.ComparisonControl.new(root, {
  stockChart: stockChart
});

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Searchable Comparison Control

Implement search functionality: 
const comparisonControl = am5stock.ComparisonControl.new(root, {
  stockChart: stockChart,
  searchable: true,
  searchCallback: (query) => {
    // Get already compared series
    const compared = stockChart.getPrivate("comparedSeries", []);
    const main = stockChart.get("stockSeries");
    
    // Build list of available securities
    const securities = [
      { label: "Apple", subLabel: "AAPL", id: "AAPL" },
      { label: "Microsoft", subLabel: "MSFT", id: "MSFT" },
      { label: "Alphabet", subLabel: "GOOG", id: "GOOG" },
      { label: "Amazon", subLabel: "AMZN", id: "AMZN" },
      { label: "Tesla", subLabel: "TSLA", id: "TSLA" },
      { label: "NVIDIA", subLabel: "NVDA", id: "NVDA" },
      { label: "Netflix", subLabel: "NFLX", id: "NFLX" }
    ];
    
    // Filter by search query
    const filtered = securities.filter(item => 
      item.label.toLowerCase().includes(query.toLowerCase()) ||
      item.subLabel.toLowerCase().includes(query.toLowerCase())
    );
    
    // Mark already-compared items as disabled
    const comparedIds = compared.map(s => s.get("name"));
    filtered.forEach(item => {
      if (comparedIds.includes(item.id) || main.get("name") === item.id) {
        item.disabled = true;
      }
    });
    
    return filtered;
  }
});

toolbar.controls.push(comparisonControl);

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Handle Selection

Respond to comparison selection: 
comparisonControl.events.on("selected", (ev) => {
  addComparisonSeries(ev.item.id);
});

function addComparisonSeries(ticker) {
  const series = am5xy.LineSeries.new(root, {
    name: ticker,
    valueYField: "Close",
    valueXField: "Date",
    xAxis: dateAxis,
    yAxis: valueAxis,
    calculateAggregates: true,
    legendValueText: "{valueY.formatNumber('#.00')}"
  });
  
  const comparingSeries = stockChart.addComparingSeries(series);
  
  // Load data for the ticker
  fetch(`/api/data/${ticker}`)
    .then(response => response.json())
    .then(data => {
      comparingSeries.data.setAll(data);
    });
}

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Removing Comparisons

Remove a comparison series: 
stockChart.removeComparingSeries(comparingSeries);
When all comparisons are removed and autoSetPercentScale is enabled, the chart automatically exits percent scale mode.

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Comparison Series Settings

Apply custom settings to all comparison series: 
const stockChart = root.container.children.push(
  am5stock.StockChart.new(root, {
    comparingSeriesSettings: {
      strokeWidth: 2,
      valueYShow: "valueYChangeSelectionPercent"
    }
  })
);

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Legend Integration

Comparison series automatically appear in the stock legend with close buttons: 
const valueLegend = mainPanel.plotContainer.children.push(
  am5stock.StockLegend.new(root, {
    stockChart: stockChart
  })
);

valueLegend.data.setAll([valueSeries, volumeSeries]);
When a comparison series is added, it appears in the legend with a close button that removes the comparison.

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Complete Comparison Example

import * as am5 from "@amcharts/amcharts5";
import * as am5xy from "@amcharts/amcharts5/xy";
import * as am5stock from "@amcharts/amcharts5/stock";

// Create root and stock chart
const root = am5.Root.new("chartdiv");
const stockChart = root.container.children.push(
  am5stock.StockChart.new(root, {
    autoSetPercentScale: true
  })
);

// Create main panel with axes and series
const mainPanel = stockChart.panels.push(
  am5stock.StockPanel.new(root, {})
);

const valueAxis = mainPanel.yAxes.push(
  am5xy.ValueAxis.new(root, {
    renderer: am5xy.AxisRendererY.new(root, {})
  })
);

const dateAxis = mainPanel.xAxes.push(
  am5xy.GaplessDateAxis.new(root, {
    baseInterval: { timeUnit: "day", count: 1 },
    renderer: am5xy.AxisRendererX.new(root, {})
  })
);

const valueSeries = mainPanel.series.push(
  am5xy.CandlestickSeries.new(root, {
    name: "MSFT",
    valueXField: "Date",
    valueYField: "Close",
    highValueYField: "High",
    lowValueYField: "Low",
    openValueYField: "Open",
    xAxis: dateAxis,
    yAxis: valueAxis
  })
);

stockChart.set("stockSeries", valueSeries);

// Add legend
const valueLegend = mainPanel.plotContainer.children.push(
  am5stock.StockLegend.new(root, {
    stockChart: stockChart
  })
);
valueLegend.data.setAll([valueSeries]);

// Add comparison control
const comparisonControl = am5stock.ComparisonControl.new(root, {
  stockChart: stockChart,
  searchable: true,
  searchCallback: (query) => {
    const tickers = [
      { label: "Apple", subLabel: "AAPL", id: "AAPL" },
      { label: "Alphabet", subLabel: "GOOG", id: "GOOG" },
      { label: "Amazon", subLabel: "AMZN", id: "AMZN" }
    ];
    
    return tickers.filter(item => 
      item.label.toLowerCase().includes(query.toLowerCase())
    );
  }
});

comparisonControl.events.on("selected", (ev) => {
  const series = am5xy.LineSeries.new(root, {
    name: ev.item.id,
    valueYField: "Close",
    valueXField: "Date",
    xAxis: dateAxis,
    yAxis: valueAxis,
    calculateAggregates: true
  });
  
  const comparingSeries = stockChart.addComparingSeries(series);
  
  // Load data
  fetch(`/api/data/${ev.item.id}`)
    .then(response => response.json())
    .then(data => comparingSeries.data.setAll(data));
});

const toolbar = am5stock.StockToolbar.new(root, {
  container: document.getElementById("chartcontrols"),
  stockChart: stockChart,
  controls: [comparisonControl]
});

// Load main series data
valueSeries.data.setAll(msftData);

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Accessing Compared Series

Get list of currently compared series: 
const comparedSeries = stockChart.getPrivate("comparedSeries", []);
console.log("Comparing", comparedSeries.length, "securities");

comparedSeries.forEach(series => {
  console.log(series.get("name"));
});

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Comparison Limits

Limit the number of comparisons: 
const comparisonControl = am5stock.ComparisonControl.new(root, {
  stockChart: stockChart,
  searchable: true,
  searchCallback: (query) => {
    const compared = stockChart.getPrivate("comparedSeries", []);
    
    // Limit to 5 comparisons
    if (compared.length >= 5) {
      return [{
        label: "Maximum 5 comparisons already selected",
        id: "limit",
        info: true
      }];
    }
    
    return getSecurities(query);
  }
});

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Comparison Colors

Comparison series automatically get different colors from the chart’s color set. Customize individual series colors: 
const series = am5xy.LineSeries.new(root, {
  name: ticker,
  valueYField: "Close",
  valueXField: "Date",
  xAxis: dateAxis,
  yAxis: valueAxis,
  stroke: am5.color(0xFF0000),
  fill: am5.color(0xFF0000)
});

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Events

Monitor comparison state: 
stockChart.onPrivate("comparing", (comparing) => {
  if (comparing) {
    console.log("Chart is in comparison mode");
  } else {
    console.log("Chart is in normal mode");
  }
});

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Data Requirements

Comparison series must have:
  • Same date field as main series
  • At least a close value
  • Data covering similar time range
const comparisonData = [
  { Date: 1617192000000, Close: 123.45 },
  { Date: 1617278400000, Close: 125.67 },
  // ...
];