Rocket Companies announced a $1.75 billion deal to acquire Redfin. The mortgage titan hopes to leverage Redfin to take market share.

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.

Redfin is being acquired in an all-stock transaction that values the real estate listing platform at $1.75 billion.

Shares in Redfin leapt roughly 70% in premarket trading after Rocket Cos. agreed to buy the online real-estate brokerage in a $1.75 billion deal. Rocket stock fell 14%. Get the details:

One of the biggest mortgage lenders in the U.S. announced this week that it plans to buy a well-known real-estate brokerage — and the deal, once it goes through, could have major consequences for millions of home buyers.

Redfin CEO Glenn Kelman on the benefits of joining Rocket: "Homes.com is running a Super Bowl ad, and Redfin might not be able to afford that. At least not on our own, but Rocket ran a Super Bowl ad."