This would be the biggest commercial real estate deal since Blackstone’s acquisition of office landlord Equity Office Properties Trust in 2007 for $39 billion, including debt. It comes as the Federal Reserve is widely expected to raise interest rates later in the year, pushing up financing costs. GE and Blackstone declined to comment. “We’re in that sweet spot of 2007 when there’s a lot of money, commercial real estate looks really attractive, and you could do some mega deals,” said Ken Riggs, president of Situs RERC, a firm does commercial real estate valuations.