In the ever more competitive world of stock analysis, any bit of raw data about a company that could be used to infer revenues or earnings is useful. Supply chain managers, and other professionals are often uniquely positioned to see this data. Sharing this data with outsiders though is illegal - it is insider trading.
The FT reports the case of Tony Longoria, a supply chain manager at Advanced Micro Devices who was moonlighting as a consultant for "Primary Global Research". Allegedly Mr L. was providing detailed information about AMD's shipments right before the company released earnings. He and several others now face insider trading charges.