PGI currently controls $200m (£124.7m) of premiums and the combined business will control around $600m worth of premiums.
“The opportunity for the group in North America is significant, but it has always been vital to us that we only enter markets where we identify people with a similar energy and dynamism to Hyperion,” said chief executive David Howden.
“PGI have the perfect blend of strong leadership and underwriting culture to match our ambitions and they will make a great platform on which we will build our US and Latin American underwriting presence.”
Earlier this year Hyperion received a substantial investment from private equity house General Atlantic, which valued the company at around £250m. This investment was designed to help the company grow at a far faster rate.
PGI currently has offices in California, Florida, Georgia, Maryland, New Jersey and New York.