A pair of lawsuits seeking class-action status accuse Hilton Hotels (NYSE: HLT) management of breaching their fiduciary responsibility to shareholders when they agreed to sell the company to The Blackstone Group (NYSE: BX) for $20.1 billion. The investors claim the size of the offer was inadequate, and the $560 million break-up fee Hilton will have to pay Blackstone if it backs our of the deal is excessive. The amount is so large they contend, that it effectively guarantees that the private equity firm will go home with the prize.

There are a couple of interesting things about this. First, the break-up fee does seem excessive. The idea of a break-up fee, ideally, is to compensate the prospective buyer for its time/use of resources if a deal fails to go through. The $560 million figure would give Blackstone a huge windfall if the deal fails to go through. While the lawsuit is unlikely to go anywhere, I would ask Hilton why such a large break-up fee was necessary.

Second, this shareholder angst may be one of the factors that will lead to the decline of the buyout boom. In recent months it seems, shareholders have grown increasingly feisty in taking on buyout offers they deem too low. This wave of shareholder activism, which often leads to higher buyout prices, can cut into the private equity firms' margin for error.

But this is probably a good thing: If a private equity firm can take a company private and make a ton of money, it might make more sense for the company to stay public and provide that value to shareholders.