I can’t find anything from a Google search that indicates Hitler’s market manipulation is a direct cause of Saturday closure. The most frequently cited reason is to give time to catch up on paperwork. Though that explanation is in tension with this post on Stack Exchange^[Stack Exchange] which also says that the market closed because trading was light during the Depression (so, which is it, there is too much work or too little?).

If this is supposed to be common knowledge, it’s hard to find details on it.