Wait, the Dow Jones was a real index during the 1940s, though it's unclear if it operated normally during the war. But in a fictional context, maybe the German forces were trying to manipulate or predict the stock market as part of their economic warfare. The radio broadcast could be a cover for sending out coded financial information.
Maybe the story is about the Nazis trying to predict the stock market trends using intercepted information, and the radio broadcast is their way of testing their theories or sending out their predictions to their network. The protagonist is an Allied agent trying to stop them.
Potential title: "Sendung 1 Dow: Shadows over Wolf's Lair"