Rocket Cos.’ $9.4 billion planned acquisition of loan servicer Mr. Cooper Group would put one in six U.S. mortgages under Rocket’s purview, according to the companies. That would create a mortgage behemoth.

Fintech firm Rocket Companies said on Monday it would buy home loan services provider Mr Cooper Group, its second big deal this month.

Mr. Cooper Group (COOP) stock surged 16% in Monday premarket trading after the mortgage servicer agreed to be acquired by Rocket Companies (RKT), creating a company that will service more than $2.1B in loan volume.