11.7% of the float is short, not huge for a biotech but sufficient to create forward momentum as shorts cover. Some may hold off to see if Bydureon tanks AMLN, but signs point to approval. Those still short if Bydureon is approved will truly be squeezed. With an Oct. 12 PDUFA for Vivotrol and Oct. 22 for Bydureon, I would expect the smarter shorts to try their best to manage some more or less orderly covering over the next few weeks. But the market is an unruly beast so their odds of success are less than optimal.