Joe Francica spoke to Clint Reiser from ARC who explained:
ARC Advisory Services GIS Market research report is based upon revenue in GIS from these services
S/W and services
The Esri market share number of 40+% was for the entire GIS marketplace.
ARC Advisory Services criteria for defining the GIS market included software that performed basic mapping functionality from pin mapping to spatial analysis (Point in polygon, network tracing; linear referencing). Hardware revenue associated with the software sale was excluded as part of total revenues. Revenue for geospatial data sales was also excluded as was project lifecycle management solutions.
Reiser also noted that his research indicated that the total size of the GIS market was between
$1.6 M to $1.7M $1.6 B to $1.7B (corrected from M to B 11/22 am, sorry for the confusion)
--- original post 11/18/11 ---
ARC Advisory Group estimates Esri's worldwide market share at 40.7 percent in its 2010 report, Geospatial Information Systems Worldwide Outlook. The report affirms that Esri is the GIS market leader in both the water/wastewater and the oil and gas distribution industries. The report also shows Esri and Esri partner Telvent as market leaders in the electric transmission and distribution industries.
I think that's the highest percentage I've seen for any company in any of these reports ever.
- press release