A prominent hedge-fund manager has been accused of using his influence at investment bank Jefferies Group to profit from buying shares in MyTheresa, a Neiman Marcus Group e-commerce spinoff.

Dan Kamensky, founder of hedge fund Marble Ridge Capital LP, faces an investigation by Justice Department bankruptcy watchdogs into whether he pressured Jefferies as part of his plan to secure shares in Neiman’s lucrative MyTheresa business at a steep discount.