Following three consecutive months of signs of greater stability in design activity, the Architecture Billings Index (ABI) fell precipitously, dropping more than six points.  As a leading economic indicator of construction activity, the ABI shows an approximate nine to twelve month lag time between architecture billings and construction spending. The American Institute of Architects (AIA) reported the September ABI rating was 41.4, down sharply from the 47.6 mark in August (any score above 50 indicates an increase in billings). The inquiries for new projects score was 51.0.  This is also the first time in 2008 that the institutional sector has fallen below the 50 mark.