S&P 500 · Rolling Return Instrument
The same index, the same monthly closes, run through ten different rolling windows — from six months to twenty-five years. Each panel below re-annualizes the trailing return at every point in time, so a short window jitters with every scare and rally while a long window settles into the market's slow, underlying drift. Click any panel to bring it into focus, or layer several on top of each other to see where the horizons agree — and where they don't.
Each series is the S&P 500's total price change over the trailing window, converted to a
compounded annual rate: ((Pₓ / Pₓ−w)^(1/years) − 1) × 100.
That puts every horizon on the same footing — a 6‑month window and a 25‑year window
both read out in "percent per year," even though one is dominated by the latest headline and the
other has lived through several full market cycles. Values below zero mean the index was lower,
annualized, than where that window started. Flip Inflation‑adjusted above to
run the same calculation on CPI‑deflated (constant‑dollar) levels instead of nominal
ones — that's the difference between what the index said you made and what it was
actually worth in today's purchasing power.
Click a panel to load it into the instrument above.