> separation of powers issues ... in the background
Under the Exceptions and Regulations Clause in Article III, every federal court exercises its power at the sufferance of Congress (apart from cases under SCOTUS's original jurisdiction). Securities-fraud cases brought by the SEC are creatures of federal statute, not (non-existent) federal common law (cf.Erie), and so the Seventh Amendment jury right arguably doesn't apply. Under the E&R Clause, Congress could authoritatively say so, overruling past SCOTUS ipse dixit extensions of the Seventh Amendment to analogous cases.
Yup. If this isn't Congress' intent, all they have to do is pass a law saying so. "...when Congress addresses a question previously governed by a decision rested on federal common law the need for such an unusual exercise of lawmaking by federal courts disappears." - MILWAUKEE v. ILLINOIS via Wikipedia.
Under the Exceptions and Regulations Clause in Article III, every federal court exercises its power at the sufferance of Congress (apart from cases under SCOTUS's original jurisdiction). Securities-fraud cases brought by the SEC are creatures of federal statute, not (non-existent) federal common law (cf. Erie), and so the Seventh Amendment jury right arguably doesn't apply. Under the E&R Clause, Congress could authoritatively say so, overruling past SCOTUS ipse dixit extensions of the Seventh Amendment to analogous cases.