What if the goal is not merely preventing your shares from being lent out without your knowledge?
What if they were already lent out without your knowledge?
So, I asked.
I was told that if the account is a margin acct. then shares could be lent out without you knowing.
BUT, if there was a GTC order placed, (like Jack mentioned) but after shares were lent out, then the broker would go buy back the shares in the market to replace the shares from the accnt that were lent out.
So, if that is correct, then Jack's GTC order idea should work both to prevent your shares from being lent out without your knowledge, & ALSO to replace them even after they were lent out, AND even in a margin accnt.