It's been decades since negative leverage was a regular unwelcome guest in commercial real estate. Now it's a trend again, according to Moody's Analytics, between growing loan interest rates and cap rates.

For those in the industry who are too young to have knowingly felt the impact of negative leverage, the concept is simple. Whereas many will say the three ls of real estate are location, location, and location, it might be truer to say that they are more leverage, leverage, and leverage.

In CRE, typically you use borrowed money to buy properties and ultimately make money. Until recently, 70% or 80% loan to value ratios weren't unheard of, and that was fine. Interest rates were only barely above ground, prices past the global financial crisis were on the rise, and so were rents. The internal rate of return was far better on all that cheap leveraged money than on unleveraged.