NO! It's a message board myth. It does NOT work that way. You can set a sell order at 5000 USD and they will still loan out your shares. The only thing you can do besides getting your share certificates (the only 100% sure thing) is change your account from a margin account to a cash account. Legally the broker is not allowed to loan out your shares in a cash account. That doesn't mean that they wouldn't do it in certain cases (if they don't care about the legal implications) but most of them do accept that rule.