I will throw my 2 cents for you incase silver don,t answer.

In shorting there is an uptick rule.

This means that any shorter cannot sell while the little arrow is/green when they place an order. They have to wait for someone to sell to turn the arrow red before they can place their short order.

Its not much of a regulation/prevention, as you can see, you just have to call a buddy to sell 100 shares to change the uptick arrow to a downturn arrow,

IMO