To ban short-selling of stocks is to short-circuit an important mechanism through which people share their knowledge and expectations with others. Banning a mechanism that better allows share prices to reflect the expectation that the underlying assets are not worth as much as current market prices suggest does nothing to change the underlying reality. Such a ban merely distorts knowledge of this reality.
My optimism about the future, which as recently as yesterday was real, is truly beginning to fade. The news about the SEC’s ban on short-selling is annoying; this news about a "vast bailout" is distressing.