Brookfield is considering purchasing General Growth Properties, and GGP's investors love it.

GGP shares traded higher today after reports broke that Brookfield held preliminary discussions with the retail REIT regarding acquiring it and taking it private. The two companies discussed a premium of 10% to 15% above GGP's per-share stock price when trading began on Monday, Bloomberg reports.

GGP stock ended the trading day at $22.20/share, up nearly 17%. Brookfield consolidated its outstanding warrants to buy GGP stock in Q3 and entered the final three months of the year owning nearly 35% of GGP stock. Toronto-based Brookfield bought its first stake in GGP in 2010, part of an agreement to bring the REIT out of bankruptcy. It acquired more stock in 2013 and agreed to maintain its stake at below 45% for the next four years, an agreement that ended in January.

Brookfield has entertained buying more GGP stock before, most recently in January 2016. The pressures that e-commerce has put on retail real estate has hit Class-A shopping malls especially hard, and operators have scrambled to fill dark space and reposition malls with more entertainment options and food courts. The shaky state of shopping malls has also made mergers and acquisitions attractive propositions.