The reverse of a share forward accumulator. More specifically, it is a structured product that involves investors taking on the obligation to sell a certain number of shares or currency on a regular basis at a fixed price. To that end, the investor writes a call option to the counterparty, with the obligation to sell a fixed number of underlying assets on a regular basis at the strike price. Therefore, decumulators don’t give the option to either party to refrain from exercising. The strike price is typically settled on a periodical basis, and hence the investors are said to be decumulating holdings in the underlying stock over time to maturity.

Investors buy decumulators on the expectation that a certain stock will trade within a specific price range, in a bear market, during the term of the contract. This range is bound by the strike price and a barrier price (usually a knock-out that triggers termination if the underlying price goes below a threshold). On the other side, the issuer sells a decumulator in the hope that the underlying will exceed the strike price.