What is sequential laying?
Sequential laying — Sequential laying is laying off the legs of an accumulator one at a time as each match plays out, instead of laying the whole acca all at once.
Sequential laying is the technique of laying the legs of an accumulator one at a time, as each match plays out, instead of laying the whole acca up-front against a single multi-runner exchange market. The lay stake on each leg is recalculated as the previous legs settle.
Sequential laying is the standard approach for any acca insurance reload — Bet365's Saturday football promo, Sky Bet's variant, Paddy Power's similar offer. The acca insurance refunds the stake (usually as a free bet) when exactly one leg fails, which means the per-leg lay sizing depends on the conditional probability of every other leg winning and the residual value of the refund. There is no single exchange market that prices the "exactly one fails" condition, so the lay can't be done all at once. Sequential laying handles the recursion: lay against leg 1, see what happens, recompute, lay against leg 2, repeat.
The full per-leg sizing arithmetic is in the sequential laying guide, and the calculator that runs the recursion lives at /calculators/standard under the sequential-lay mode. The acca-specific Smarkets workflow is in the laying-accas guide.
Worked example
Take a clean 2-leg version to see the recursion. £20 double on two football matches, each leg priced at 2.0 (total acca odds 4.0, profit £60 if both win). Bet365's acca insurance refunds £20 as a free bet if exactly one leg fails, which is extractable for around £15 on a typical SNR free bet workflow.
Before leg 1 kicks off, lay against leg 1 at the exchange at lay-odds around 2.05. The lay stake is smaller than a flat-double lay would suggest, because the leg-1-loses outcome is partially recovered by the free-bet refund (the loss that needs balancing is £20 cash minus the ~£15 extractable refund value, not the full £20). If leg 1 wins, recompute the leg-2 lay against the residual single. If leg 1 loses and the acca dies, the refund mechanic activates. The same principle scales to 4-folds, 5-folds and longer accas — the per-leg stake compounds with the surviving acca probability and updates each time a leg settles.
Common mistake
Leg 1 wins, and you forget to lay leg 2 before kickoff — or the exchange's liquidity dries up at leg 2's kickoff time and the lay can't be placed at fair odds. Sequential laying requires being available inside narrow pre-kickoff windows for every remaining leg. The reliable strategy is to confine sequential-lay accas to weekend slates where the kickoffs are predictable and clustered, and not attempt them across midweek matches scattered between Tuesday and Thursday. If you can't be at a screen when each leg starts, lay the acca flat against a multi-leg market instead and accept the smaller extracted value.