What is the origin of the word "stocks" in finance?

The word stock comes from the Old English stocc, which means “stump, post, stake, tree trunk, or log." It is derived from the Proto-Germanic stauk-, which means “tree trunk or stalk" The word stock was used to refer to the equity instruments that represent ownership in a corporation or similar entity since the early 17th century, but the exact reason why it was used to refer to equity ownership is unclear. It could be the idea of a tree's "trunk" from which gains are an outgrowth, or it could derive from an obsolete use of the word stocc as a "money-box."