What are we to make of REITs? These trusts, which trade as equities and are essentially collections of real property, or mortgages, became widely reviled when the real estate bubble collapsed in late 2008. Domestic and global REIT mutual funds plunged 39.6% and 46.6%, respectively, according to Morningstar. But REITs joined the S&P in regaining a lot of ground last year, delivering an average return of 20% in 2009. Despite huge vacancy rates in malls, office buildings and multifamily housing complexes, many REITs in the $250 billion market performed well, particularly in the second half of the year, when they returned just slightly less than the S&P. Domestic and global REIT mutual funds were up an average of 31% and 37%, respectively, according to Morningstar.