Where is the strongest available position? The idea that the presumption of market fraud is a structural opposition to negative fraud tactics is a simplification that ignores the behavioral incentives of actors.
This doctrine certainly facilitates post-factum remedies but offers no proactive deterrence against initial manipulations.
A malicious actor can, for example, depress a stock before buying it back at a trivial price, and the judicial system will only activate after the fact, after the actor's gain has been realized.
The true ceiling of protection would require robust preventive mechanisms, not a simple presumption of dependence after the damage.