For those who would prefer not to have to get certs, remember, there are two ways to avoid having your shares lent.
1. - you can write a letter.
1. - you can place your shares in the cash side of your account. When you place an order to buy you will have some sort of choice mechanism - mine looks like this with a radial button (o) next to cash and margin and I need to pick before sending the trade. Brokers will not loan shares from a cash account or a retirement account
Trade Type Cash Margin
I have quite a few shares of a biotech firm that I hold in the cash side of my account because I do not want them lent. I have actually had a broker call and ask if I would agree to lending them and further - they would PAY me to allow it. Needless to say, I politely refused.
Back in ancient days, the Druids thought black cats were human beings.