Domicile vs. Protocol: Empirically Disentangling Regulatory Risk Premiums in the Post-GENIUS Act Era

the GENIUS Act's prohibition of issuer-paid interest. We identify three distinct pricing mechanisms: protocol-driven dynamics, strategically administered rewards, and evolving regulatory risk premiums. During baseline conditions, protocol selection dominated yield determination, with spreads far exceeding regulatory domicile effects. However, an October 10, 2025, exogenous tariff shock created a natural experiment: DeFi yields responded elastically, spiking from 4.25% to 22.6% on Aave, while custodial rewards remained administratively fixed. By November 15, 2025, Coinbase executed a strategic pivot, aggressively promoting on-chain wallet rewards (4.70%) over custodial products (3.85%). This maneuver exploited a "distributor loophole," allowing Coinbase yields to exceed DeFi rates while maintaining legal distance from issuer prohibitions. Concurrently, the regulatory risk premium for offshore stablecoins expanded from an insignificant 0.05% to 0.47%, driven by intensified enforcement and security incidents. These findings reveal that stablecoin yields are shaped by sophisticated regulatory arbitrage and platform-specific incentives. The results offer critical implications for the pending CLARITY Act, Responsible Financial Innovation Act, and the future of issuer-centric digital asset regulation.