Definition
Pool hopping is a strategy in which a miner directs hashrate to a pool only when each submitted share is worth the most, then withdraws once expected value drops. It is not a hardware exploit but an economic one, profiting at the expense of loyal miners by timing entry and exit around a pool's reward accounting.
Why proportional pools are vulnerable
The attack targets the proportional reward scheme, where a found block is split among miners by their share of the current round's shares. Early in a round, after a block was just found, few shares exist, so each new share claims a disproportionately large slice of the eventual reward. A hopper mines aggressively during these short, share-poor rounds and leaves once the round grows long and per-share value falls, capturing more than its fair contribution, by some analyses up to roughly 28 percent extra.
How modern pools defend
The defense is the reward scheme itself. Pay Per Last N Shares (PPLNS) prices shares using a long trailing window rather than a single round, so there is no short round to exploit. Pay Per Share (PPS) and Full Pay Per Share (FPPS) pay a fixed value per share regardless of when a block is found, removing the timing incentive entirely. This is why almost no major Bitcoin pool still runs a pure proportional model.
See how the resistant schemes work in our PPLNS and FPPS entries.
In Simple Terms
Pool hopping is a strategy in which a miner directs hashrate to a pool only when each submitted share is worth the most, then withdraws…