Pooled stake

Running a validator takes a server and a minimum stake (10,000 USD on the devnet). Pooled stake lets anyone add stake to a validator they choose, from one unit up, without running anything and without handing the stake over. The stake counts towards the validator’s weight, earns a share of its rewards, and shares its risk.

A delegation is yours

A delegation is an object its delegator owns, like a coin. It holds shares of the validator’s pool; the pool holds the stake. The operator never controls it: only the delegator can collect its rewards, undelegate or withdraw, and there is no pool token to lose or lend.

Delegating just before an epoch ends earns nothing for that epoch: a delegation earns only for epochs it was in the pool for from start to end.

How rewards are split

Validators are paid from fees only (see Rewards). At the end of each epoch, each validator’s reward is split between its own stake and its pool’s earning stake, in proportion to their sizes. The operator keeps a commission on the pool’s part; the rest is credited to the pool per earning share, with an exact integer accumulator, so a delegator is owed exactly its shares’ part, rounded down.

An example (our arithmetic): validator v stakes 100,000 of its own; its pool’s earning stake is 50,000, alice’s 30,000 and bob’s 20,000; its commission is 10 %; its reward for the epoch is 30 USD.

Rewards stay credited until collected, whatever happens to the validator later. Rounding left over by the accumulator stays with the pool’s unclaimed rewards.

The commission

• At most 25 %.
• It takes effect at the end of the epoch in which it is set, after that epoch’s rewards: a change never applies to an epoch already under way, so delegators see it before it applies, and can leave.
• Once anyone has delegated, it rises by at most 2 percentage points at a time (one change per epoch takes effect). A pool nobody has joined may start at any commission up to the ceiling. Lowering is always allowed.

Concentration

A delegation is refused if it would give its validator more than twice an equal share of the bonded stake of all joining and active validators, and the cap is never below a tenth:

Bonded stake here counts the validator’s own stake and its pool’s earning and pending stake. The cap bounds what delegation can concentrate; a validator’s own stake is not capped.

Shared risk

If a validator equivocates, it loses all of its own stake, as before, and its pool loses a tenth of its stake. Every share loses the same fraction, pending and unbonding delegations included: undelegating does not escape a slash until the stake is withdrawn. Evidence is not bound to a time, so a delegation made after the offence but before the report is slashed too. The reporter’s share (5 % on the devnet) is of the validator’s own stake only; the pool’s tenth goes to the treasury whole. (As first written, v1.11 paid the reporter a share of the pool’s tenth too: an operator whose pool was about 190 times its own stake could then profit from reporting itself through another account, since header evidence never expires. A review of the economics found it, and it was changed before release.)

In the example, if v equivocates: its 100,000 is forfeited, the pool loses 5,000, alice’s delegation is worth 27,000 and bob’s 18,000, and the reporter receives 5 % of 100,000, 5,000. Delegators keep the rewards already credited to them.

Choosing a validator is therefore a real decision: its commission, its record and how much of its own stake it puts first.

The weight of a validator

At each epoch’s end, validators rank for the active set by their own stake plus their pool’s earning stake, and that sum is their weight in consensus and in sampling lane committees. Unbonding stake does not count.

In this implementation

• Built (specification v1.11, §5.45 to §5.49 and the epoch end in §6.3): delegations, shares, joining at the epoch’s end, the reward split with an exact per-share accumulator, commission rules, the concentration cap, collecting, undelegating, unbonding, withdrawing, and the pool’s share of a slash; the ranking by own plus earning pooled stake. Both proof stacks implement it; the differential tests run every rule and every way it can fail through both, check every epoch end’s split against a third, plain-arithmetic reading, and run randomized workloads of delegations, claims, commission changes, fees and slashings, checking the pools against the delegations they hold after every Pulse.
• Commands: sion stake pools, delegate, show, claim, undelegate, withdraw and commission, and the MCP tools sion_stake_*. See Delegating stake.
• Simplified: every pool lives in one shared object in the validators’ domain, so delegation transactions are ordered one after another; a pool slash is a flat tenth whatever the offence; the stake asset is fixed at genesis (the devnet stakes USD, a test asset).
• Not built: moving a delegation to another validator without unbonding; delegating from an agent’s budget; reward compounding.