How the US AI 100 is built

Methodology version 1.0. List date Oct 2, 2026. Base 1,000.

This index

Each day's move is the average of the members' returns, each weighted by its value at the previous close. A company joining, leaving, splitting its shares or issuing new ones changes the weights, never the level.
Public members are valued at market cap and move with their split-adjusted share price. Dividends are not reinvested.
Private members are valued at the list's valuation, moved each day by their average secondary-market share price across platforms. A mark older than ten days is not used; with none, the value holds.
During the session the level is recomputed every five minutes from prices delayed 15 minutes. The official value is the close.

Every index is built from the same list of US companies building AI, chosen by our editors. A change to the list applies from its own date and never rewrites earlier days.
Share counts and earnings come from filings made by each day, so a later restatement never changes an old value.
Before the list date the values are a back-test of the companies picked that day, each from its first trading day.
A day whose prices cover too little of the index, or whose level moves more than 8%, is held for review before it is published.

Sources: company filings, exchange prices and secondary-market trades.