There are a few reasonably ready ways to do this.
First, if you know the proper name of the insurer, go to its website and there will likely be an article or notice to policyholders concerning the change of structure or ownership.
You can also contact the insurance commissioner's office in the capitol of your state. Assuming that the company does business in the state in which you live, there would need to have been regulatory filings made/approved. There is likely Division of Consumer Services from which the information is available. Alternatively, check through the Division of Insurer Services.
Finally, you may be able to get the information from the website of the National Association of Insurance Commissioners (See link below).
Who bought The Life Insurance Company of Virginia
What company bought out Members Life Insurance Company
i need info on Texas Reserve Life Insurance Company in San Antonio Texas
Who bought ranson industrial life insurance company
Met Life
Who bought The Life Insurance Company of Virginia
What company bought out Members Life Insurance Company
They have been bought out by American General Life & Accident
SBI life insurance company
If you write to the company with your query, they will supply the information you require.
who bought roosevelt National Life Insurance Company of America
Are you sure you are not looking for National Western? https://www.nationalwesternlife.com/ No, there was a Western National Life Insurance Company of Amarillo, Texas that existed as of 12/31/1995--the last document I can find. Now I need to find out who bought out the company. Western National Life Insurance Company was bought out by American General Life Insurance Company, which was then purchased by AIG. WNL now does business as AIG Annuity. See www.aigannuity.com for contact information.
Safeco Life Insurance Company
Reassure America Life Insurance Company, Jacksonville, IL
americo
axa
Imperial Life Insurance Company of Asheville, NC was bought out by Western and Southern Life Insurance Company of Cincinati, Ohio.