FA-61399 / Options payoff and settlement / Member archive

Contract adjustment for splits and special dividends: the new deliverable keeps fractional shares · case 04

Deliverables such as 166.67 shares are produced for 5-for-3 splits.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Inputs strike, contracts, deliverable, action and value. split [new, old]: if new is a multiple of old (ratio r), strike becomes strike/r rounded half-up to cents and contracts become contracts*r; otherwise the deliverable becomes floor(deliverable*new/old) with strike and contracts unchanged. special_div of at least 0.125 per share reduces the strike by the amount (rounded half-up to cents). Other actions, including ordinary_div, change nothing. Return [strike, contracts, deliverable].

Why this case matters

Option expiry, exercise and settlement engines move cash and shares; a wrong branch misstates obligations.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression fractional deliverable 1	`[33.33, 10, 166.66666666666666]`	`[33.33, 10, 166]`	Failed

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