March 12 (Reuters) - Shares of cement maker Summit Materials Inc, controlled by Blackstone Group LP, rose as much as 12.5 percent in their trading debut on Thursday, valuing the company at $1.87 billion.
The initial public offering of 22.2 million Class A shares, priced at $18 each, raised about $400 million.
The stock opened at $20.16 and touched a high of $20.25, valuing the company at about $1.87 billion. About 5.1 million shares changed hands in early trade, making them the second-most traded on the New York Stock Exchange.
Summit Materials' valuation takes into account 92.26 million outstanding shares, if all outstanding LP Units held by the limited partners of Summit Materials Holdings LP were exchanged for newly issued shares of Class A common stock, according to the filing.
Summit Materials Holdings is the predecessor company for financial reporting purposes.
Only 26 companies listed in the United States so far this year, down from 47 in the same period in 2014, according to Thomson Reuters data.
Citigroup and Goldman Sachs & Co are the lead underwriters of the offering. (Reporting by Amrutha Gayathri in Bengaluru; Editing by Joyjeet Das)