Accumulator is financial derivative product. Last financial crisis, Hong Kong folks dubbed this pain investment as "I kill you later". How does it work...
Basic idea is an issuer (banker/broker) sells accumulator contract to buyer (investor) for a underlaying stock at a predetermined fixed price (strike price), settled periodically. this allows the investor "accumulate" the underlaying stock over the term period of contract.
An investor agreed to "accumulate" 100 shares a month at fixed price of $80/share for one year contract. Below diagram illustrated for scenarios of underlaying stock go up and down.
Bear in mind, all investment products have its risk.