Apparently there are companies/scammers that somehow get wind that you hold shares of company stock and offer to purchase those shares from you, FAR below market value.
If you are solicited by them, just trash them, and post about them online to help others not get scammed.
Prudential Financial Recommends Shareholders Reject Unsolicited Mini-Tender Offer from Potemkin Limited
It blows me away that there are companies like that which are allowed to exist to solicit in such a scamming sort of way, rather than buy/sell within the trading market like normal.
Solicitation like this should be punishable.
EDIT0: WOW! I take it there are mini-tender solicitors on this sub. Hey, you're scum. Deal with it. It shouldn't be controversial/questionable.