One of the biggest mortgage lenders in the U.S. said it would pay $1.75 billion to buy a well-known real-estate brokerage. The deal, once it goes through, could have major consequences for millions of home buyers.

Rocket Companies agreed to acquire Seattle-based Redfin in a $1.75 billion deal that will bring together the nation's largest mortgage

Dan Gilbert's Rocket Companies plans to buy the online real estate brokerage firm Redfin, a $1.75 billion deal that would expand Rocket's presence in all things residential real estate. The all-stock deal was announced Monday morning and, pending approval by Redfin shareholders, is expected to close in the second or third quarter.