U.S. insurance companies are making heavy investments in real estate.

These firms make up a large part of the institutional investor base, and 23% of the ones buying real estate hold between $1 billion and $5 billion as of September 2012, according to Carla Henry, a researcher at Preqin.

On average, real estate made up 2.1% of total insurance company assets, worth roughly $961 million.

And if they're not buying properties straight up, they're investing in companies that do.

Gladstone Land, a real estate investment trust that acquires agricultural real estate, got a new $4.8 million line of credit over the next five years with MetLife (MET) in June. It adds to the existing $45.2 million line it already had with the insurance giant.

On Wednesday, Gladstone filed a $58 million IPO.

Read more from Henry here.