Aspen Insurance Holdings (AHL) said late Wednesday it priced its upsized $397 million initial public offering of roughly 13.3 million Class A shares at $30 apiece.

Underwriters have a 30-day overallotment option to buy up to an additional 1.9 million shares, according to a statement.

The offering is expected to close on May 9. Shares are expected to start trading on the New York Stock Exchange today under the ticker AHL, the company said.