How it works
Ex-rights price = (cum-rights close + rights ratio × issue price) ÷ (1 + rights ratio + bonus ratio). With only a bonus issue it is close ÷ (1 + bonus ratio).
Ex-rights date
The ex-rights date is the business day before the record date. With T+2 settlement you must buy by the day before the ex-rights date.
What to keep in mind
A bonus issue adds shares without adding value, so the price adjusts down. The market price after the ex-date still moves with demand.