Deep Fission is a pre-revenue nuclear energy startup developing the Gravity Reactor, a small modular reactor (SMR) designed for installation one mile underground in deep vertical boreholes. The company adapts established pressurized water reactor technology for a subsurface form factor, using surrounding geology and hydrostatic pressure for containment and shielding. This design aims to reduce capital costs and improve security compared to above-ground plants. Each reactor produces up to 15 MWe, and Deep Fission plans to cluster units for large-scale customers. The company is executing a three-phase commercialization plan, beginning with engineering validation at its Kansas site where it has drilled a data acquisition well. Deep Fission targets a demonstration reactor in H1 2027, followed by commercial licensing for hyperscale data centers, utilities, and industrial facilities. The business model includes project-level equity participation to earn revenue from power purchase agreements, upfront fees for reactor delivery, and recurring licensing and maintenance fees. Deep Fission intends to use project-level financing for installations to scale deployments without carrying the full capital cost on its balance sheet. The technology is currently in early engineering stages and has not generated revenue.