It stands for auto-callable yield note; a structured note in which the coupon is linked to more than one underlying (usually two indexes), and is callable quarterly. It has a maturity ranging between 1-3 years, and allows the holder (investor) to receive a coupon (say 8.00%) as long as the lesser performing index is above a specific level (e.g., 65%) of its initial level. The note has a knock-in mechanism which helps trigger redemption if the index declines by a preset percentage (e.g., a knock-in at 60% which translates to a 40% decline in any index).

If a knock in occurs, the investor receives a redemption amount equal to the principal value minus the performance of the lowest performing index, and the coupon payment is stopped. If no knock-in occurs, the investor receives the coupon (8.00% ) and full principal (100% of face value) back at maturity.

ACYN may also denote an autocallable contingent yield note.