It's where you buy something like a promissory note or bond that guarantees to pay out X at a future date for a discount, e.g. you pay 90c now for a $1 bond that matures in say 2 years time. Shares do not have that guarantee so they are not an 'adjusted financial instrument' - which are referred to as 'financial arrangements' in the Income Tax Act. The discount of X versus the future receipt is treated as taxable income with various methods for allocating across multiple financial years, where applicable.