Glossary entry
An index is a calculated measure used to summarize changes in a defined group of observations, such as securities, prices, or economic data. A financial index follows selection, weighting, and maintenance rules that determine what it represents. The level is a measurement convention; percentage changes usually convey more than comparing the absolute levels of unrelated indexes.
Illustrative example
An index moving from 2,000 to 2,100 rises 5%. Another rising from 100 to 105 has the same percentage change despite a different point movement.
What to consider
Indexes are calculations rather than directly owned assets. Products tracking them can have expenses, tracking differences, and risks absent from the published index.
General information, not a personal recommendation. Product availability, rights, and obligations are determined by the relevant provider, jurisdiction, and approved agreements.