The self-assembly of short amphiphilic molecules of type A(2)B(2) (A=hydraphilic, B=hydrophobic) is investigated using Stochastic Dynamics simulations with a scalar frictional coefficient. Equilibrium properties were calculated and explained in the context of existing thermodynamic theories. Spherical micelles are observed to form and the effect of temperature and total surfactant concentration on the structural properties are investigated. Above the critical micelle concentration, a decline in the free surfactant concentration is observed, contrary to existing theories dealing with micelle formation. The observed behavior can be explained in terms of excluded volume effects. Excellent agreement is obtained between the resulting predictions and the simulation results over the entire concentration range.