The last time something like this happened SLV depositied a large sum into it's vaults. The price subsequently ran to $48. Reflecting back this was also the time where it was rumored(?) that JPM was forced to stay out of the futures market while the CFTC conducted their "investigation".
Maybe it's HSBC's turn on the back of their drug smuggling profits to come under fire from many different directions. Maybe they're just buying for some of their finest clients. You know, converting their greens (not backs) into silver???