The chart above was created using a tool posted last Friday on thomsonreuters.com. It calculates the theoretical results of replacing any component of the Dow with Apple.
The component to be replaced turned out to be AT&T — the company that Steve Jobs talked into carrying the original iPhone.
The switch is scheduled for March 19.
Follow Philip Elmer-DeWitt on Twitter at @philiped. Read his Apple (AAPL) coverage at fortune.com/ped or subscribe via his RSS feed.