1) In the case of a variable annuity, a measurement of the value invested in the account during the accumulation period of the contract. The more funds you contribute to your annuity account, the more accumulation units you will build.

2) In the case of a unit trust, a type of investment structure where the trust's income is directly reinvested into the trust, instead of being paid out as cash to the investor.

1) Accumulation units are used to accurately measure the value of contributions by the annuitant. In times when the variable annuity's investments dip, a fixed amount of funds will buy more accumulation units than when the securities are more highly priced, just as investors are able to by more shares of cheaper stock than they can of higher priced stock with the same amount of currency.

2) Accumulation units within a unit trust can be reinvested back into the trust via boosting the unit price, or issuing additional units to investors. Either way, the investor is able to reinvest their share of profits back into the trust.