From McBrearty v. Vanguard Group, Inc., 2009 U.S. App. LEXIS 25675 (2d Cir. Nov. 20, 2009):

To state a civil RICO claim, plaintiffs must show that they were injured "by reason of" the alleged racketeering activity, 18 U.S.C. § 1964(c), that is, that the defendant's RICO violation proximately caused plaintiffs' injuries.... In the RICO context, proximate causation means, in turn, that "the alleged violation led directly to the plaintiff's injuries." Anza, 547 U.S. at 461. Here, however, the complaint alleges that the decline in the funds' online gambling holdings was not the direct result of the RICO violation — the owning and/or financing of illegal gambling — but rather was the result of the subsequent "government crackdown" on the illegal gambling. Although plaintiffs contend that the law enforcement crackdown was a foreseeable risk of defendants' activities (rather than a supervening cause), we have already held that proximate causation is lacking under RICO when the harm results from the exposure or disclosure of the RICO predicate activity. In re Am. Express Co. S'holder Litig., 39 F.3d 395, 400 (2d Cir. 1994).

[Footnote 1] Although foreseeability is often the test of proximate causation at common law, see Palsgraf v. Long Island R.R. Co., 162 N.E. 99, 100 (N.Y. 1928), RICO causation is a concept distinct from "proximate causation as that term is used at common law." Abrahams v. Young & Rubicam Inc., 79 F.3d 234, 237 (2d Cir. 1996).

[Footnote 2] Although plaintiffs argue that American Express is undercut by the Supreme Court's recent decision in Bridge v. Phoenix Bond & Indemnity Co., 128 S. Ct. 2131 (2008), we do not agree. The civil RICO action in Bridge was brought by regular bidders at a county's auctions of tax liens, who alleged that the defendants, also regular bidders, were able to obtain a disproportionate share of valuable liens by lying to the county about their status as "related entities" in order to circumvent a rule that would otherwise result in a more equitable distribution of liens.... Thus, the injury alleged in Bridge — the plaintiffs' inability to obtain valuable liens to which they would otherwise have been entitled — resulted directly from the fraudulent representations that constituted the racketeering activity.