It may be unrelated, but read this: http://www.zerohedge.com/news/2017-07-27/350-trillion-securities-limbo-libor-be-phased-out-2021. You're right we could be looking at a market failure here, as you're not the only one with missing shares. There isn't enough money in the kitty to pay everyone back. The good news I suppose is the OTC always does well when the regular markets aren't doing well.