Louis A. Movitz, as Trustee, and Estock Corporation, N v. V. First National Bank of Chicago, Cross-Appellee

POSNER, Chief Judge.

A jury awarded Estock Corporation some $3.3 million in damages in a diversity suit against the First National Bank of Chicago for breach of contract and of fiduciary duty. The bank appeals, and Estock cross-appeals seeking the addition of prejudgment interest to the judgment. The principal ground of appeal, and the only one we shall have to consider, is that Estock failed to prove that the bank’s conduct was the “cause” of its loss within the meaning that the law attaches to this term when a plaintiff is seeking an award of damages. The applicable law, the parties agree,…