Definition of 'Nominee'; (http://www.investopedia.com/terms/n/nominee.asp)
A person or firm into whose name securities or other properties are transferred in order to facilitate transactions, while leaving the customer as the actual owner.
A "nominee account" is a type of account in which a stockbroker holds shares belonging to clients, making buying and selling those shares easier. In such an arrangement shares are said to be held in street name.
We can only speculate on who actually owns the shares, i.e. who is JPM's customer. I doubt it is JPM themselves. Do some research and you will find JPM Nominees (or other Nominees) as top holders in many ASX companies, most of which have nothing to do with silver. Westpac is only one example of many (http://www.spankyourbank.com.au/wbc-top-twenty-shareholders). JPM Nominees hold nearly 13 %.
Cheers
AYN Price at posting:
5.3¢ Sentiment: Hold Disclosure: Held