You can come up with "long term" (hold times of weeks I guess) trading ideas with nothing more than close prices right? On the assumption that you only ever tr

You can come up with "long term" (hold times of weeks I guess) trading ideas with nothing more than close prices right? On the assumption that you only ever trade the auction you'd be getting a reasonable approximation of your actual experience. I mean, I'm not sure I accept the premise that there's enough information there to find significant alpha - but if you assume that he's using a different data source for that, he can test the trading performance on close prices alone.