There can be little doubt that those shorting shares of SLV, the largest silver ETF in the world, are doing so because the required amount of physical silver is not available to secure and deposit as required by the prospectus.
And finally, let's plot copper and silver together over the same period shown above. You can plainly see the long-term correlation. You might also note that silver currently appears to be undervalued by about half.
In silver -- the biggest drop was in SLV inventories, down a whopping 27.035 million troy ounces, followed by the COMEX, down 5.160 million troy ounces. After them came SIVR, down 1.816 million troy ounces...and 843,000 troy ounces out of iShares/SVR.