The damage is not transient, but long-lasting. Once these "short" shares have been manufactured out of thin air by use of the market-maker's exemption (known as the "Madoff Rule"), there is no way to make them disappear again. The end result is a dilution of the company's float to an unknown degree. The only way to reduce the float to its nominal size again is to issue new shares, which I have never heard of actually happening; on the surface, it would be a poor use of corporate funds, especially for a small-cap stock like Arena Pharmaceuticals.
This post represents my opinion only!