Momenta could easily use $75mil of their cash hoarde and announce that they'll buy the 4.2 mil shares back on the open market. The $75 mil won't be missed and the buyback would lift the earnings per share by about 10%.
Maybe this is the fire that would make the street sit up and take notice. For Mnta's management to only pay a $15 million dollar premium at this point would more than be rewarded by the street's impression that Momenta is confident in its future.