Economic origin — spin-offs inherit their parent’s founding year
1800
180018501900195020002010
Performance, 1980 – 2025
Founding dates — cumulative distribution (CDF)
All six indices in one chart · by index weight
Read a line left to right: at any year on the x-axis, its height is the share of that
index’s weight founded in or before that year. A line that climbs early belongs to an old
index; one that stays low until the 1970s–90s is a young index. The dashed vertical line is your
current cutoff — everything to its left is the weight the filter flatlines.
CAC 40, FTSE 100 and Nikkei 225 are drawn from their five founding-era cohorts, so their curves
are interpolated across the cohort bands (1900, 1950, 1970, 1990) rather than built from
individual companies. The curves are lightly smoothed; the table below keeps the exact shares.
How the adjustment works
The rule
Each constituent keeps its index weight for the whole period. If its founding year is before the
cutoff, its price is frozen at the 1980 level — a 0% return every year — while every younger
company compounds as modelled.
filtered(t) = Σyoung wi · Pi(t) + Σold wi · 100
Founding year = economic origin
A spin-off, demerger or privatisation does not reset the clock. The year shown is when the
underlying business began, even if the listed vehicle is much younger — which is why the
“listed” column in the tables below is separate, and often decades later.
Today’s constituents are back-filled over the whole period (a survivorship-biased simplification,
fine for a mockup, worth stating out loud).
Examples — lineage calls in this data
Siemens Energy — 1847, not 2020. The spin-off inherited Siemens’ power business; the firm is 19th-century, the listing isn’t.
Deutsche Post (DHL) — 1947, not the 2000 IPO. Traced to the Deutsche Bundespost, founded in the British zone in 1947.
Constituents — who gets flatlined?
Weights are approximate current index weights, held constant