The term goodwill is usually associated in an aquisition in which the purchase price exceeds the fair market value (FMV) of the assets received in consideration. It is considered an intangible asset and actually speaking, it is. It's more like a premium you would pay on a company that has good management or some other "hard to nail down" quality that makes it more valueable than the naked assets would be on the open market.
Negative goodwill is the opposite mathematical equation. it means the assets were purchased for less than their FMV. Now, JPM was required to disclose this in their 10Q for GAAP/SEC purposes (imo), but it seems like a bad move to me to have put the fact in broad daylight by intervening in the case. Talk about greedy. It just goes to show that they went to court to protect the fact that they got way too good a deal. WABOFC's!
(what a bunch of ------- crooks)