So all we need is regulation against DDoS and concentrated sale orders and we are all warm fuzzier again? Great! Who wants to lead the SRO?

Or does more regulation do anything?

Computer Fraud and Abuse Act, or 18 U.S.C. §1030

As far as the large sell order/volume strategy is concerned, that's just a market and the sellers would be taking a market risk with this behavior. It's not naked shorting.

Dumping shares into a thin market is a standard practice in every single regulated market around the world. LBO/Hedge Funds firms frequently engage in this practice to undermine confidence in a company with lots of debt and thin margins to scoop up the secured debt/preferred equity at a corresponding discount a gain control of the company.