Abstract

This study tests whether the organic growth rates of United Kingdom (UK) life insurance firms are independent of size, as predicted by Gibrat's (1931) Law of Proportionate Effects. Using data for 1987–1996 and the three subperiods, 1987–1990, 1990–1993, and 1993–1996, we find that smaller life insurance firms tended to grow faster than larger ones in the 1987–1990 period and that larger life insurers tended to grow faster than smaller ones in the 1990–1993 and 1993–1996 periods. But over the ten-year period, we find no significant difference between the growth rates of small and large firms, thus supporting Gibrat's Law as a long-run tendency in the UK life insurance industry. When we examine firm-specific determinants of asset growth, we find evidence in 1987–1996 and 1987–1990 that more diversified life insurance firms experienced higher growth rates on average than more specialized life insurers. We also find that the growth of life insurance firms was related to input costs during the 1990–1993 and 1993–1996 subperiods.