Shifting money between sectors as conditions change, on the view that different industries lead at different points in an economic cycle. It asks you to be right about two things at once, the cycle and the timing, which is why it is harder in practice than it reads. PSEye's sector pages show each sector's combined market cap and constituents, and the analytics page's correlation matrix shows which sectors have actually moved together rather than which ones are supposed to.
See every term in the full PSE investing glossary.