In order to get a conviction, shareholders would have to prove : 1) that such cooperation existed 2) that it violated existing laws 3) that they personally suffered losses as a result.
3 looks to me hard to prove by itself, but the real problem is of course condition 2. An action that was the result of directly following a court order is not illegal, not even if it violates laws (that's the whole point of court orders, after all).
I would be interested in what would happen if they did get a conviction. This would be a weird situation. Shareholders own IBM, after all. So any damages paid would effectively be a transfer from one part of their ownership to another, effectively a zero-worth transaction.