The market for commercial real estate loans is coming back, but already some industry professionals are warning that risky practices that were common in the recent boom are returning.

An increasing number of financial institutions are vying to make loans on commercial real estate now. But many buildings are still drowning under heavy debt loads, leaving few properties that can support new borrowing. This means that banks, insurance companies, hedge funds and others are competing fiercely to underwrite the few viable loans that are available. Because of the competition, some lenders have begun to compromise their underwriting standards, say ratings agencies and market professionals.