The energy sector is undergoing an unprecedented transition characterized by the rapid integration of renewable generation, large-scale storage, and electrification to achieve net-zero carbon emissions. This transition necessitates corresponding reforms in electricity market design. Short-term prices, central to electricity market design, not only support efficient daily operations, but also inform long-term entry and exit decisions. However, price caps and offer caps in many systems restrain high prices, creating a need for capacity payments to address the "missing money" problem, i.e., prices in short-term markets for energy and ancillary services are suppressed below the level required to support resource adequacy. These payments are calibrated under the assumption that price suppression occurs only in instances of scarcity, such that market operators can restore theoretically efficient remuneration by tying capacity payments to estimates of production during scarcity events. However, the complexity of power system operations together with increasing renewables and large-scale storage create challenges with short-term price formation that can lead to price suppression in non-scarcity hours as well. Chapter 2 conducts high-fidelity simulations of operations to show that missing money can arise from algorithmic decisions across all hours rather than solely during scarcity, and that compensating for it through capacity payments leads to inefficient remuneration. Beyond short-term operations, liberalized electricity markets often include resource adequacy mechanisms that require consumers to contract with generation resources well in advance of real-time operations. Chapter 3 investigates how the financial hedge embedded in alternative resource adequacy contract designs can induce different responses from risk-averse investors, with consequences for the resource mix and market structure. A stochastic equilibrium model is developed to simulate a competitive market with incomplete risk trading and to compute investment equilibria under different contracting regimes. Results indicate that system operators should allow resources contracted through other means to opt out of mandatory capacity mechanisms, subtracting their contributions from administratively defined demand curves to avoid inefficiency of crowding out other forms of risk sharing. Alternatively, regulators could replace capacity obligations with shaped forward energy contracts for greater risk sharing and better outcomes for consumers if they wish to promote a single contractual form. Finally, transmission expansion is critical to facilitate the energy transition, but disputes over cost allocation present a significant barrier to investments in both regional and interregional projects. Chapter 4 analyzes this challenge by constructing a model for transmission and generation expansion planning under uncertainty as well as the calculation of benefits for network users. Results confirm the potential for realized benefits at the participant level to differ significantly from ex ante estimates. Several key cost allocation issues associated with "beneficiaries pay" principles are discussed. Collectively, this dissertation underscores the importance of refining short-term price formation, resource adequacy mechanisms, and transmission cost allocation to advance a reliable, effective energy sector transition.