The transfer of risks already undertaken from one insurance company to another is?

An insurance company that accepts a large or unusually risky policy may not want to carry the whole of that risk itself, in case a claim turns out to be very large. To protect itself, the company can pass part of the risk it has already accepted on to another insurance company.

This practice of one insurance company transferring part of a risk it has already undertaken to another insurance company is called re-insurance. It spreads the potential loss across more than one insurer, so no single company is left exposed to the full cost of a major claim.

Under insurance and over insurance describe a mismatch between the sum insured and the true value of the property being insured, not a transfer of risk between insurers. Group insurance is a single policy covering many people together, such as employees of one company, which is also unrelated to shifting risk from one insurer to another.

Whenever a question describes risk moving from one insurance company to another after it has already been accepted, the correct term is re-insurance.