I have come to own this upright piano labelled "Joint Stock". No other label or mark visible. I am unable to find out anything about its provenance. Any ideas?
Weirdly enough, some history texts refer to a "joint-stock piano" (no capitals) as a standard item. Example:
First, Dickens wrote that many boarding houses had a joint-stock piano. Apparently, to Englishmen this would seem like a luxury not fitting for workers.
Many piano mfrs became "joint-stock" companies, which doesn't help us either. However, my guess is that this particular piano might be a 'custom' item produced by some manufacturer to celebrate 'going public' and becoming a joint-stock corp. Maybe someone who is an expert in Dickens & his history knows more about the origin of this term.
It was suggested that I post an answer. Comments in Carl's answer lead me to this site
Their piano B7 looks about right:
So it looks like the piano is by Joint-stock company Muzinstrument - Borisov, from Belarus.