Power
You may not be able to bend a steel bar into a "U," but still—you're pretty powerful. Major company financing decisions can hinge on your say-so, and you can affect quite a change, for better or for worse. If for worse, be careful—someone might be so ticked off that they try bending a steel bar around your neck (well, in Russia, maybe).
If a company wants to buy more of its competitors and they ask your thoughts, you might say, "I am supportive if you pay fifteen times earnings or less; if you pay twenty times earnings I would likely downgrade you," that speaks volumes. The company might be cowed into not making the acquisition for fear that you, their big Street supporter, would lose faith and move on. The pen here really is mightier than the sword.