We argue that power markets are shifting from generation-driven systems to flexibility-driven systems. As renewables push marginal costs toward zero and negative pricing becomes more common, value is moving from producing energy to shifting it across time and location. Early battery economics were dominated by ancillary services, but those markets quickly saturated. Today, energy arbitrage is the primary revenue driver. Across both capacity and energy-only markets, storage is emerging as the central asset, signaling a structural transition toward what can be described as a “storage market.”$SIGN