Nielson claims that JP Morgan uses each ounce of the SLV fund's silver to back a short position. In other words, JP Morgan is using their SLV investors' long silver positions to back JP Morgan's short positions. He suggests that each single ounce of silver is therefore used to back two opposing positions: long and short.
"JP Morgan has a gigantic personal incentive to try to make sure that holders of SLV units make as little as possible on their investment", he argues.
See Jeff Nielson's posting "SLV and silver manipulations".