Conflicting forces in Miami’s office market led to an unusual situation this quarter as rents for available space fell in spite of marked tightening in the rental supply, a report from broker CBRE Inc. shows.

Office vacancy rates in Miami’s metro market tightened by 80 basis points to 16.6 percent, the CBRE report released last week said. That was the largest drop in vacancy rates of any of the 13 U.S. markets surveyed by CBRE. Vacancies in downtown Miami fell even faster by 90 basis points to 18.2 percent.