SAN FRANCISCO (TheStreet) -- Digital Realty Trust said rental revenue more than doubled last year. Digital Realty, a real estate investment trust, booked record 2010 annual leasing performance in terms of square footage and total contract value of $1.2 billion, the company said, representing a 160% increase over results in 2009. >> 10 Top Buy-Rated Real Estate Stocks for 2011 Investors bid shares sharply higher in morning activity but the stock pared gains ninety minutes into the session, trading 0.1% lower at $51.70.