There are trades that get "busted" (i.e. rolled back) every day in the US stock markets. I've had it happen several times. This is part of normal market activity. In my experience it has seemed pretty subjective - some trades that I thought for sure would have been busted weren't and others were.
There's some speculation that when some more powerful market participants (read: Goldman Sachs) are on the losing end of a questionable trade they complain to the exchange and get the trade busted far more frequently than when it happens to less powerful participants.
There's some speculation that when some more powerful market participants (read: Goldman Sachs) are on the losing end of a questionable trade they complain to the exchange and get the trade busted far more frequently than when it happens to less powerful participants.