Interesting video below discussing some of the history involved in the silver market. It focuses on the Hunt Brother's attempt to corner the silver market to send prices higher back in 1980, and then discusses Barclay's and JP Morgan's attempt to manipulate the silver market downward today.
It is worth noting that the entire above ground supply of silver today would be about $35 billion to purchase. That is a flick of dust in relation to the global markets.
A buyer will wake up one morning, similar to the Hunt Brothers did in 1980 and Warren Buffett did in 1997, and decide they want to remove all remaining supply.