Running Commentary on the SP Movements., page-3248

No but I have seen the gold and silver markets do exactly this. The banks got caught not too long ago fixing the markets - precisely because they had information we didn't - in that case it was because they knew exactly where everyone's stop losses were.

So they'd co-ordinate between banks (different brokers) to run huge short positions, trigger the stop losses and then run longs.

If you go back through Zerohedge you can read up the phone transcripts between the brokers - callous asshats.