According to Wall Street Journal:
“Capitalization rates, used by real-estate investors to measure the annual return of income-producing properties, rose in August even as yields on 10-year Treasury notes dropped, resulting in a wider gap between the rates. The average cap rate for office properties in central business districts was 6.46% in August, up from 6.35% in July. For apartment buildings, it was 6.37%, from 6.36%. Yields on 10-year Treasury notes, meanwhile, fell to 2.3% in August.”