What was the biggest trade mistake your team made within the last five years?

It's hard to pick out a bad trade since we've had the upper hand in trades.. But if I had to pick one it would have to be the Halladay Trade. Yeah we got awesome prospects but think about it he had 2 no hitters last season so he could've had one with the Jays, and it might've given them a post-season run last season.