How have courts treated allegations of market manipulation in the context of a securities transaction?

[C]ase law in this circuit and elsewhere has required a showing that an alleged manipulator engaged in market activity aimed at deceiving investors as to how other market participants have valued a security. ATSI, 493 F.3d at 100. The gravamen of manipulation is deception of investors into believing that prices at which they purchase and sell securities are determined by the natural interplay of supply and demand, not rigged by manipulators. Gurary v. Winehouse, 190 F.3d 37, 45 (2d Cir.1999). In identifying activity that is outside the natural interplay of supply and demand, courts generally ask whether a transaction sends a false pricing signal to the market. ATSI, 493 F.3d at 100.