Kosmos Energy Ltd.'s stock gained 5 percent in its first day of trading on the New York Stock Exchange.
The oil exploration and production company's shares traded at $18.85 midday on Wednesday, above its offering price of $18 per share.
Kosmos said last month that it expected to offer 30 million shares for between $16 and $18 per share. Its initial public offering contains 33 million shares.
The underwriters were given an option to buy up to an additional 5 million shares to cover any excess demand.
Kosmos is trading under the "KOS" ticker symbol.