Abstract: Methods for executing fractional shares transactions are disclosed. In one aspect, a method for executing a fractional-based buy or sell order may be performed by a fracker processing unit (FPU) configured with an on-hold queue, in-progress queue, fracker balancer, and fractional share database, where a fractional share component of the buy or sell order is subjected to the method. In another aspect, a method for executing a notional-based buy order may be performed by FPU, where an estimated fractional share component of the notional-based buy order is subjected to the method. In another aspect, a method for executing a executing a notional-based sell order may be performed by FPU, where a quantity of an executed whole share component of a notional-based sell order is subjected to the method. In another aspect, a method for executing fractional shares transactions may be performed by in part, providing cleanup account shares to FPU.