Donegal Mutual Insurance Company, or Donegal Mutual, organized us as an insurance holding company on August 26, 1986. At December 31, 2018, Donegal Mutual held approximately 43% of our outstanding Class A common stock and approximately 84% of our outstanding Class B common stock. Donegal Mutual's ownership provides Donegal Mutual with approximately 72% of the combined voting power of our outstanding shares of Class A common stock and our outstanding shares of Class B common stock. Our insurance subsidiaries and Donegal Mutual have interrelated operations due to an intercompany pooling agreement and other intercompany agreements and transactions we describe in Note 3 of the Notes to Consolidated Financial Statements. While maintaining the separate corporate existence of each company, our insurance subsidiaries and Donegal Mutual conduct business together as the Donegal Insurance Group. As such, Donegal Mutual and our insurance subsidiaries share the same business philosophy, the same management, the same employees and the same facilities and offer the same types of insurance products.
At December 31, 2018, we had four segments: our investment function, our personal lines of insurance, our commercial lines of insurance and our investment in Donegal Financial Services Corporation, or DFSC. We set forth financial information about these segments in Note 19 of the Notes to Consolidated Financial Statements. The personal lines products of our insurance subsidiaries consist primarily of homeowners and private passenger automobile policies. The commercial lines products of our insurance subsidiaries consist primarily of commercial automobile, commercial multi-peril and workers' compensation policies.
Our insurance subsidiaries and Donegal Mutual provide their policyholders with a selection of insurance products at competitive rates, while pursuing profitability by adhering to a strict underwriting discipline. Our insurance subsidiaries derive a substantial portion of their insurance business from smaller to mid-sized regional communities. We believe this focus provides our insurance subsidiaries with competitive advantages in terms of local market knowledge, marketing, underwriting, claims servicing and policyholder service. At the same time, we believe our insurance subsidiaries have cost advantages over many smaller regional insurers that result from economies of scale our insurance subsidiaries realize through centralized accounting, administrative, data processing, investment and other services.