Accumulators (aka: share forward accumulators) are financial derivative products sold by an issuer (seller) to investors (the buyer) that require the issuer to sell shares of some underlying security at a predetermined strike price, settled periodically. This allows the investor to "accumulate" holdings in the underlying security over the term of the contract.

The basic idea of an accumulator contract is that the buyer speculates a company will trade between a certain price range (the range between the strike and the knock out price) within the contract period, and the issuer bets that stock will fall below the strike price. Note that the buyer holds an obligation to buy the shares at the strike price and not the option to buy. Likewise, the issuer holds an obligation to sell shares at the strike price.

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