How each close is worked out
Every line starts from the same place: the Forbes reading of $1.051 trillion on 6 October 2026. To it we add what his holdings have gained or lost since that day’s close: 413,152,109 Tesla shares, and 5,116,475,230 SpaceX shares and options, each multiplied by the change in its share price. Nothing else moves, so the figure changes only when a price does.
We take the line after 4pm New York, once the market has shut, using the closing prices the site’s Calculate now fetches. Each line in the file carries both prices it used, and this page works the dollars out again from them before showing anything. A line whose dollars do not follow exactly from its prices is left out, so a typo can never reach the table.
Why it is exact to the dollar
Because it is arithmetic on whole share counts and published prices, and the sum lands on a whole number of dollars. The Forbes reading it starts from is rounded to the nearest $1 billion, and his private holdings are carried at that reading’s value, so the last digits show the arithmetic, not a precision anyone could claim for his whole fortune.
Just after the open
On trading days we also take a line at 10am New York, half an hour after the market opens, once the opening rush has settled into the day’s first steady prices. Until that day’s close arrives, the morning line leads this page and the home page, measured from the close before it, so you can see how the day has started. In the table it sits beside the close it belongs to. A day’s change is still always close to close.
Weekends and holidays
US markets close at weekends and on public holidays, so those days have no line. A change in the table is always measured from the close before it, however many days apart they are.