Hi LuckyWon,
No, no insight to share but by having a look at the intra-day chart:
http://finance.yahoo.com/q/bc?s=ABT.TO&t=1dIt looks like one trade sends the stock down (#20$) and then a lot of trades (and a bigger volume in total) brings it back to 23$.
It might be a big player who wanted to shake the stopper and made this one big sell and a lot of little buys to get some shares cheaper.
Or just one guy jumping out of the stock and a lot of other ones reloading on the opportunity, who knows???
And by the way, that's the kind of reason why we stay out of stop orders. In that particular case, and if it stays like that we would have jumped out of the stock for no reasons.