It's been a solid year for General Growth Properties ( GGP); shares of the $16 billion real estate investment trust have climbed more than 12% on the year, a time when the S&P has only managed to hold onto 4.7% of its gains. Pension funds have been buying that strength in the last quarter, effectively doubling their positions in the stock with 14.5 million more shares. GGP owns interests in approximately 170 regional shopping malls across the U.S., a business that provides the firm with a combination of consistent lease income and a smaller cut of retail sales at its properties. As a commercial REIT, it's best to think of GGP as an income generation vehicle; the firm rents out stores using long-term triple-net leases that keep volatile expenses like taxes, insurance, and maintenance off of GGP's list of responsibilities. The result is fairly predictable income that must be mostly paid out to shareholders each quarter. That's not to say that GGP hasn't had its share of issues in the past. The REIT went bankrupt in 2009 when the collapse of the credit markets made it impossible for the firm to renegotiate its large mortgage debt load. While the firm re-emerged from bankruptcy stronger (and at a time with borrowing costs at historic lows), the drama left a bad taste in investors' mouths - that could factor into a cheaper valuation in shares. Investors should be paying attention to the 2.4% dividend yield in shares right now. GGP also shows up in Bill Ackman's portfolio as of the most recently reported period.