“Sell in May and go away” is the adage that the November–April stretch has historically outperformed May–October, suggesting you exit equities for the summer. There's real long-run data behind the seasonal gap — and real reasons it's a poor basis for actual trading decisions.
The data behind it
Over long histories, the winter half-year has tended to produce stronger average equity returns than the summer half. Proposed explanations include lighter summer liquidity, vacation-season disengagement, and seasonal fund-flow patterns. The effect is measurable across decades — it's not pure myth — which is precisely why it persists as a talking point.
Why it doesn't survive as a rule
The gap is a small average over many years with enormous variance: plenty of strong summers, plenty of weak winters. Mechanically selling every May would have missed major summer rallies, and after costs and taxes the “edge” largely evaporates. It's a statistical curiosity about long-run averages, not a reliable timing signal — and treating a weak seasonal tendency as a directional mandate is the classic seasonality trap.
A real pattern and a tradeable one are different things. “Sell in May” is real on a 50-year average and useless on any given Tuesday.
What it means for a scalper
For a 0DTE scalper it's nearly irrelevant to your actual decisions: you're trading intraday structure, not holding for six months. At most, it's a reminder that summer months tend toward lower volume and volatility — useful context for your expectations, not a reason to be directionally biased. Read the live map; let the calendar adage stay a footnote. NoVo trades the structure in front of it regardless of the season.