Hi tocents. Market cap is computed using fully diluted outstanding shares. The discrepancy in shares outstanding and shares held by institutions is because of late reporting and shorting. I believe that nearly 100% of the 14 million Insmed shares shorted have been shorted by institutions.
Insty A owns 5 Million shares. Insty B borrows all 5 Million and shorts them to Insty C. Both Insty A and C have to file a form 13f as 5% owners, which they do in fact own, but it does not account for the 5 Million shares loaned out to be shorted. So between Insty's A,B and C, there is a NET long position of 5 Million shares, but 10 Million in institutional ownership.
Does that make any sense?