If a multi-employer fund is fully funded, as the Western Conference Fund was until a few years ago, and as some other funds were in the past, then UPS would not owe any money to the fund for retirees of dead companies. It's only if the fund's assets drop, that UPS and other currently contributing employers must make up the shortfall. That's the built-in insurance feature of multi-employer funds that UPS agreed to.
UPS chose to pull out of Central States at a time when its assets had fallen significantly, and so it owed a huge Withdrawal Liability payment. Kind of like getting out of the stock market by selling your stock after the market has hit bottom.
There is no negotiating in determining the amount of Withdrawal Liability. UPS owed the debt, and when Central States was informed of UPS' intention to withdraw, they calculated the amount and sent UPS the bill as the law requires.
I know how tempting it is to think that a professional money manager should be able to manage money and make a healthy rate of return, but apparently it just isn't that simple. Lots of professionals make only a small return, or even loose money. Of course, if the stock and bond and money markets all go bad at the same time, even the best investment managers will probably loose money. A falling tide lowers all boats.
Usually employers and employer trustees try to avoid contributing enough money to fund the plan 100%. So when the markets drop, it suddenly generates a financial crisis as the fund's funding level drops even further. If employers had fully funded the plan in the first place, or better still, over-funded it, there wouldn't be such a crisis. (Unions and union trustees may favor underfunding as well.) The law allows such underfunding in multi-employer funds.
In single employer funds, the law requires companies like UPS to contribute as much money as necessary every year to achieve full funding, or something very close to it. UPS has no choice, and so UPS quietly contributes the money, without any comotion.
UPS has been fully aware of the rules of multi-employer funds, and the dynamics of how they operate since they joined in the 1950s. Why do you suppose they choose to join in the first place, and stay for so long even in Central States, and agree to continue in all the other multi-employer funds into the future?
Techgrrl, is Tieguy your father? This pension stuff seems familiar.