What does net present value measure? Please describe a real-life situation or circumstance where a company might forego a positive net present value project?

As an alternative -- give an example of a real firm (in the news) pursuing a strategy (or projects) where you believe the project or strategy may not have a positive net present value.For example -- Walmart is expanding in the United States by building Neighborhood Marts.These are much smaller more convenient (closer to where you live) stores that are supposed to win back customers from the Dollar stores.I do not claim to be smarter than the management of Walmart but, I personally believe this to be a negative net present value project because I believe these store will be expensive to operate and will cannibalize sales at the existing Walmart stores.What are your examples and why?