Bubble charts are Scatter Plot charts where a third dimension of data is represented by the sizes of plotted objects.



Use When

  • Displaying the distribution of a set of items relative to three variables, where the third variable is represented through the size of the plotted objects, i.e., Return %, Standard Deviation, and Portfolio Weight.

Don′t Use When

  • Displaying the distribution of items relative to only two axis variables. Instead, use a Scatter Plot.
  • Showing the statistical correlations among a set of items. Instead, use a Correlation Matrix.

Visual Language

  • Never use colors other than those defined in the visualization palette.
  • Always use the relevant color orders and meanings from the visualization palette.
  • Colored lines on each axis refer to each plot within the chart, precise axis data values.
  • Use hover crosshairs when it is important to be able to see a plotted item’s exact placement on each axis.


  • When hovering over an item in the legend, all plotted items associated with that item become opaque, while all other plotted items and legend items fade back.
  • When hovering over a plotted item, the plotted item and its matching legend item become opaque, while all other plotted items and legend items fade back. A tooltip appears, surfacing the underlying data values of the holding, including its weight within its holding group.


  • Bubble charts are fully fluid horizontally and vertically.
  • The tickers within the bubbles only appear when there is enough room.


  • Strive for short, succinct axis labels and legend items that clearly describe the data.
  • Include the unit or increment in axis labels.

Code Reference

Necessary code documentation can be found in the MBC repository.

©2017 Morningstar, Inc. All rights reserved. Terms of Use