4. Medco Health Solutions ( MHS) is a pharmacy benefit manager.
McCaskill requested that four more drug companies and three drug distributors turn over documents.
AstraZeneca calls MYSTIC results "disappointing".
Here are the activist investor's next potential targets.
AstraZeneca shares rose after the group said its CEO would host an earnings call later this month following speculation he was to take up a similar role Teva Pharmaceuticals.