W.R. Berkley Corporation is a specialty insurance holding company that underwrites commercial insurance through numerous individual operating units, each focused on specific niches like professional liability, workers' compensation and specialty property coverage. Its decentralized structure, with dozens of relatively autonomous underwriting units rather than one centralized operation, lets the company develop deep expertise in narrow insurance niches where pricing and risk assessment require specialized knowledge. As a specialty insurer, W.R. Berkley often underwrites more complex or unusual commercial risks than standard personal insurance, earning premiums that reflect the specialized underwriting expertise required to price those risks accurately. Insurance profitability depends on collecting more in premiums than is eventually paid out in claims and expenses, a relationship tracked through the combined ratio, while the company also invests its premium float to generate additional investment income.