Switched-capacitor (SC) DC-DC voltage converters are widely used in power delivery and management of modern integrated circuits. Connected to a common supply voltage, SC converters exhibit cross-regulation/coupling effects among loads connected to different SC converter stages due to the shared components such as switches, capacitors, and parasitic elements. The coupling effects between SC converter stages can potentially be used in covert communication, where two or more entities (e.g., loads) illegitimately establish a communication channel to exchange malicious information stealthily. To qualitatively analyze the coupling effects, a novel modeling technique is proposed based on the multi-port network theory. The fast and slow switching limit (FSL and SSL) equivalent resistance concepts are used to analytically determine the impact of each design parameter such as switch resistance, flying capacitance, switching frequency, and parasitic resistance. A three-stage 2:1 SC converter supplying three different loads is considered as a case study to verify the proposed modeling technique.