…
Rules (fixed before looking at results, applied to each stock's price relative to the S&P 500 so market-wide rallies do not count):
The knee is placed by fitting a two-segment line to weekly log prices; every rule is checked against the year right before that knee. Scan of ~12,000 US stocks with FMP prices, 2016 to September 2026.
Causes, first public signals and lead times were researched after the fact with web search (sources in the data table); they describe what happened, not a tested strategy. Within each group, earliest knee first. Each chart shows 6 months before its base year to 9 months after it first reached 2× (use the range control beside a title to widen it): month-end share price and price relative to the S&P 500 scaled to the price at the knee. The shaded span is the base year, the accent line the knee, the other line the month it first reached 2×. Drivers were labelled after the fact by a model and reviewed by hand; they describe what happened, not what was knowable at the knee.
new management, cost cuts, margin repair; the signal is in the company's own filings. Signal clearly public before the knee for 6 of 26.
a price the company is levered to moves: gold, oil, gas, freight, crypto; the signal is in the commodity market. Signal clearly public before the knee for 9 of 21.
COVID and other outside events; rarely knowable before the knee. Signal clearly public before the knee for 1 of 21.
spending announced elsewhere creates a shortage in an input the company supplies; the first signal is usually in other companies' disclosures. Signal clearly public before the knee for 11 of 19.
trial data, approvals, rulings; the stock often runs up into a readout whose date is known in advance. Signal clearly public before the knee for 1 of 18.
a product crosses into mainstream use, visible in usage and customer data before the financials. Signal clearly public before the knee for 4 of 16.
legislation, tariffs, reimbursement or budgets change the economics. Signal clearly public before the knee for 3 of 10.
takeovers, spin-offs, strategic stakes, index inclusion. Signal clearly public before the knee for 0 of 10.
a turn in rates or credit changes bank, insurer and homebuilder economics. Signal clearly public before the knee for 3 of 7.
the company is a levered bet on another asset. Signal clearly public before the knee for 1 of 1.
doubled within days of a spin-off; the scan likely mis-measured them