Locking-your-shares Simply Put: GTC SELL order to sell
all of your shares at a price beyond any expectations...say double or triple the pps today.
Here's why: The shares showing in your brokerage account balance aren't REALLY there. There's merely a "promise" from a MM to your brokerage, that he's good for your shares at said price.
He can sell the shares he's promised over and over again and then if YOU sell them, all he has to do is dip into someone else's promised shares.
If you have an order to sell on your shares, MMs generally avoid "playing-games" with those shares.
This makes shares scarce and buys hard to fill and the price goes up!