Share your insights or perspective on the financial matter presented in the input.

Why do shareholders participate in shorting stocks?
In short (pun intended), the shareholder lending the shares does not believe that the shares will fall, even though the potential investor does. The shareholder believes that the shares will rise. Because the two individuals believe that a different outcome will occur, they are able to make a trade. By using the available data in the market, they have arrived at a particular conclusion of the fair price for the trade, but each individual wants to be on the other side of it. Consider a simpler form of your question: Why would a shareholder agree to sell his/her shares? Why don't they just wait to sell, when the price is higher? After all, that is why the buyer wants to purchase the shares. On review, I realize I've only stated here why the original shareholder wouldn't simply sell and rebuy the share themselves (because they have a different view of the market). As to why they would actually allow the trade to occur - Zak (and other answers) point out that the shares being lent are compensated for by an initial fee on the transaction + the chance for interest during the period that the shares are owed for.