The New York Department of Financial Services is mulling whether to approve Athene Holding's $1.55bn acquisition of the UK-based insurer Aviva's US annuity business that was agreed in 2012.

An affiliate of private-equity firm Apollo Global (APO) is funding Athene Holdings for the acquisition.

The regulator is concerned that Apollo and other such investment firms would take riskier bets with policy holders’ money than traditional insurers would make.

New York Department of Financial Services head Benjamin Lawsky said that Apollo and other investment firms were involved with the contracts called fixed annuities through their relationships with insurers, reported the Wall Street Journal.

Besides Aviva’s US annuity and life insurance operations, the acquisition included Aviva Life and Annuity Company, based in Iowa, and Aviva Life and Annuity Company of New York.