NEA chart, page-416

It was just based on market psychology. Since the SP had been dropping so quickly everyone wanting to buy would have been waiting to see how low it went. It signalled the SP moving into TA behaviour rather than FA.
Eventually it had to stop though as it eventually passes too much below perceptions of what its worth in FA. Once enough people started buying all the others on the sidelines waiting to see how cheap it was getting would have had begun piling in too.
Traders who play this idea also join in and make it the reality. Its still in a TA phase imo though now on the upswing.
Its got much less to do with the company performance than the short term SP movements.

If you want to buy now rather than in 6 months it depends on whether you believe they will be able to boost their sales in the US significantly over that time or not, if they do not it will fall again post FY results, probably worse than this time. But if you do want to buy back in now I'd say hopefully we've seen the bottom. All imho