A four-switch step-down storageless DC-DC converter is provided having simultaneously ultra high efficiency of over 99% in an ultra compact size, while also providing a regulation and maintaining fast transient response while in regulation. Because of its storageless feature it is ideal for demanding computer applications, such as VRM (Voltage Regulator Modules), with extremely fast step-load load current change requirements and tight output voltage regulation requiring ultra low output ripple voltages during the transients.