All IRA's are cash-only accounts (no margin buying, no shorting), and it is my understanding that shares held in IRAs therefore are not available for shorting by others.
Personally, I am not comfortable with shorting, and in questioning myself as to why I eschew this sometimes quick route to profits, I conclude that somehow it feels "unAmerican" to me, like kicking a guy when he is down. We Americans seem to have an inbred desire to see underdogs succeed at beating the odds, perhaps because one of the foundations of our country is that here everyone has an equal opportunity, and every nobody can dream of becoming somebody one day.
And no, I didn't short 9/11 -- when the markets reopened, I bought (and am still holding that bag)!
Newly