A small piece of information can literally be worth billions, as demonstrated by Gotham Season 2. If anything, the revelation that Theo Galavan knows who killed Bruce Wayne's parents came as a shock, because it seems like the obvious thing to use to manipulate the boy. I mean, he's been mourning them since the premiere episode, and while Gordon may have promised that he would help Bruce find the culprit, he's come up empty. And, to be fair, he's basically stopped looking, especially since Bruce seemed far more invested in finding out his father's legacy and training in order to maintain it than getting revenge during Season 2.
But when Galavan suggested the exchange of control of Bruce's entire billion-dollar company for a file that allegedly has the identity of the killer, the kid nearly leapt out of his chair. Of course, after thinking it over, he couldn't agree to the terms of the deal, but when Galavan threw the file in the fire, Bruce was devastated. Even though Galavan is heading to prison for kidnapping the former mayor, he seems confident that he won't need that file anymore. Perhaps it was empty — or, perhaps he has the contents memorized, which should incentivize Bruce to potentially get Galavan out of jail, and even give up his company.
Now, of course, Galavan's motives are quite sinister. He wants to steal the Wayne fortune, and he also aims to kill Bruce, all in service of a blood rivalry between his family, the Dumas, and the Waynes, centuries prior.
The ancient nature of the conflict suggests a conspiracy: Galavan might be the one who designed the murder of Thomas and Martha Wayne in the first place. Why else would he be able to offer up the identity of the killer, a person whom no one else saw or knows? It doesn't add up perfectly (why would it take until that day to find out the man's name) and it makes the inclusion of Silver St. Cloud even more extraneous, but with all of Galavan's other evil plans, orchestrating the deaths of two innocent billionaires seems right up his ally.
Image: Nicole Rivelli/FOX