Aflac Incorporated

Aflac Incorporated is the largest provider of supplemental insurance in the United States, founded in 1955 and based in Columbus, Georgia. In the United States, Aflac underwrites a wide range of insurance policies, but is perhaps more known for its payroll deduction insurance coverage, which pays cash benefits when a policyholder has a covered accident or illness. The company states it insures "one of four Japanese households" and is "the largest life insurer in Japan in terms of individual insurance policies in force". Aflac is also well known for its supplemental medical policies.
Aflac currently is the number one supplemental health provider in the U.S., followed closely by Allstate Workplace Division. However, its market share is higher than its next four competitors combined.
In 2009, Aflac acquired Continental American Insurance Company for $100 million to expand its coverage beyond voluntary benefits alone.
As of June 30, 2012, Aflac was represented by approximately 19,300 sales agencies in Japan, and 76,900 licensed sales associates in the U.S.

Aflac Website: http://www.aflac.com/

Aetna Inc for insurance in USA .

Aetna, Inc.is an American managed health care company, providing a range of traditional and consumer directed health care insurance products and related services, including medical, pharmaceutical, dental, behavioral health, group life, long-term care, and disability plans, and medical management capabilities. Aetna is a member of the Fortune 100.
Aetna, Inc Website: http://www.aetna.com/

21st Century Insurance and Financial Services, Inc.

21st Century Insurance is an auto insurance company and is wholly owned by the Farmers Insurance Group of Companies®. They are headquartered in Wilmington, Delaware, and provide private passenger auto insurance in 48 states and the District of Columbia.
21st Century Insurance was founded in 1958 by Louis W. Foster as an inter-insurance exchange offering auto insurance, primarily in California. Initially, the company was called 20th Century Insurance.
The company was purchased in 2005 by AIG and then later sold in 2009 to Farmers Insurance Group of Companies®.
21st Century Website: http://www.21st.com