Securitization of very large commercial loans, a hallmark of the CMBS market before the financial crisis, is making a comeback — but with a twist.

It is still not practical to include commercial loans of several hundreds of millions of dollars in CMBS conduits, as was common in 2005, 2006 and 2007. That is because conduit deals have yet to reach the size that would provide enough diversification for a loan backing, say, a Manhattan skyscraper.