What actually moves a price
Net transfers. If far more managers buy a player than sell him, he rises £0.1m; the reverse and he falls. FPL does not publish the exact thresholds and they scale with ownership, which is why price-prediction sites exist and why none of them are perfectly accurate.
The 50% sell-on rule — the bit that costs people money
When you sell a player who has risen, you keep **half the profit, rounded down to the nearest £0.1m**. Buy at £7.0m, he rises to £7.3m, you sell for **£7.1m** — not £7.3m. Your purchase price is remembered per-player, so two managers holding the same player can have different selling prices.
Should you chase price rises?
Mostly, no. A £0.1m rise is worth roughly nothing next to a captaincy call or a fixture swing, and transferring early to catch a rise means committing before team news. Price is a tiebreaker between two players you already rate — never a reason to buy one you do not.