WTF 1 day old bread???
Synthetic shorts and lent shares for shorting, a routine Street money maker, is all that's there. Naked shorting is indeed possible, but that's moar than likely part of the HFT algos.
Failure rate is a problem of far, far greater importance. It's what took out both Lehman and the knuckleheads at AIG because "The Steet" stopped returning what was borrowed and just stole it as it went by. That's both Repo AND shares lent for shorts that those two were locked out of. It was Street action that was coordinated and finessed by Geithner's goofs at the NYFed. Then they smothered under the blanket party called "TARP"
"Fail to deliver" is the real deal and is fuckery within the system of the highest order.