Trading data comes in many flavors. If you're talking about the executions the bank actually performed, no, that's not going to get tossed away. On the other

Trading data comes in many flavors. If you're talking about the executions the bank actually performed, no, that's not going to get tossed away. On the other hand, if you're talking about the terabytes upon terabyte of quotes (even level 1 quotes on equities mind you), yeah, those get tossed. And key decisions get made based on that data. That stuff gets kept around for a while, but it gets deleted eventually.