“Sell in May and go away” does not beat buy-and-hold on GPN: -6.6 points a year over 26 years.
Findings derived from the full panel. Each carries its number and its denominator; the computations are reproducible with artifact 0b534dd04389.
Long from the first trading day of November to the last of April; cash from May to October. Calendar rules: simulated with our seasonal engine, same costs as everything else.
The verdict compares the strategy with buying and holding GPN over the same window, with round-trip costs per asset class. “Out of sample” is walk-forward: the rule is fit on one stretch and judged on the next. A result that beats in the full sample but not out of it is overfit. Full methodology in the protocol. How we test.
Open this backtest with its trades Trades (CSV)
Every strategy on GPN → · Full page for “Sell in May and go away” →
Finaxion Research (2026). Does “Sell in May and go away” work on GPN?. Daily backtest 1962-01-01–2026-08-31, artifact 0b534dd04389. https://finaxion.app/en/research/sell-in-may/gpn
Not a recommendation. Past performance does not guarantee future results.