This is what triggered the selloff in silver today, but the price was rather extended above trend when the news came out. The exchange gave some relief to the short interest.
CME Group to Raise Silver Margins by 30 Percent
NEW YORK, Nov 9 (Reuters) - CME Group said on Tuesday it will raise its silver futures trading margins by 30 percent to $6,500 an ounce from $5,000 an ounce effective Wednesday.
U.S. silver futures surged as much as 6 percent before retreating, with volume rising to an all-time high on Tuesday, boosted by extreme price volatility and possible short covering, traders said.
Also read Three's Company: Silver Margin Change by Jim Rickards
I do not see this as impairing the rally unless stocks undergo a sustained selloff. I would prefer to see a steadier, non-parabolic rise that slowly roasts the big short interest on a spit of their own construction.